A cycloaddition is a pericyclic chemical reaction , in which two or more unsaturated molecules or parts ... of the bond multiplicity. ref GoldBookRef title Cycloaddition file C01496 ref The resulting reaction .... This would make the Diels Alder reaction a 4 2 cycloaddition, the 1,3 dipolar cycloaddition a 3 2 cycloaddition and cyclopropanation of a carbene with an alkene a 2 1 cycloaddition. This type ... examples of thermal cycloadditions which have 4n electrons for example the 2 2 cycloaddition ... 400px center Cinnamic Acid CycloAddition Note that not all photochemical 2 2 cyclizations ... center In the i j ... cycloaddition notation i and j refer to the number of atoms involved in the cycloaddition. In this notation a Diels Alder reaction is a 4 2 cycloaddition and a 1,3 dipolar addition such as the first step in ozonolysis is a 3 2 cycloaddition. The IUPAC preferred notation however ... reaction both become a 4 2 cycloaddition. The reaction between norbornadiene and an activated alkyne is a 2 2 2 cycloaddition. Types of cycloaddition Diels Alder reactions The Diels Alder reaction is a 4 2 cycloaddition reaction. File Diels alder 1,3 butadiene Ethylene .png Diels Alder reaction Huisgen cycloadditions The Huisgen cycloaddition reaction is a 2 3 cycloaddition. File Huisgen.png 500px 1,3 cycloaddition Nitrone olefin cycloaddition The nitrone olefin 3 2 cycloaddition Nitrone olefin cycloaddition is a 3 2 cycloaddition. File NitrGen.png Nitrone olefin cycloaddition Formal cycloadditions ..., however these are not strictly speaking pericyclic reactions. When in a cycloaddition charged or radical intermediates are involved or when the cycloaddition result is obtained in a series of reaction ... cycloadditions. One example of a formal 3 3 cycloaddition between a cyclic enone and an enamine ... title Stereoselective Intermolecular Formal 3 3 Cycloaddition Reaction of Cyclic Enamines and Enones ... pmid 17146819 issue 4 ref Image 3 3 cycloaddition.svg center 600px Intermolecular Formal 3 3 Cycloaddition ... more details
wikify reason Needs some wikilinks date December 2011 The 1,3 dipolar cycloaddition , also known as the Huisgen cycloaddition or Huisgen reaction , ref cite journal title Kinetics and Mechanism of 1,3 Dipolar Cycloadditions first Rolf last Huisgen journal Angewandte Chemie International Edition volume 2 issue 11 date November 1963 pages 633 645 url http www3.interscience.wiley.com cgi bin abstract 106572717 ABSTRACT doi 10.1002 anie.196306331 format abstract ref ref cite journal title 1,3 Dipolar Cycloadditions. Past and Future first Rolf last Huisgen journal Angewandte Chemie International Edition volume 2 issue 10 date October 1963 pages 565 598 url http www3.interscience.wiley.com cgi bin ... chemical reaction belonging to the larger class of concerted, pericyclic cycloaddition s. It is the reaction ... Huisgen cycloaddition . Proof of mechanism Although this was once hotly contested, the possibility ... Concerted processes such as the 1,3 cycloaddition require a highly ordered transition state high ..., relative rates of addition for different cycloaddition reactions have been found to offer general ... in these cycloaddition reactions is varied. For example, in azide alkyne coupling reactions without ... Huisgen Cycloaddition Process Copper I Catalyzed Regioselective Ligation of Azides and Terminal Alkynes ... ABSTRACT doi 10.1002 anie.196306331 format abstract ref Image 1,3 cycloaddition between Benzonitrile ... on the conjugated substituents. Image Types of HOMO LUMO Interactions during 1,3 Cycloaddition Reactions.png ... alkyne Huisgen cycloaddition . Diazo compounds are 1,3 dipoles in the Diazoalkane 1,3 dipolar cycloaddition ... to form isoxazoline s. Ozonolysis begins with a 1,3 dipolar cycloaddition of ozone . This is followed by a retro 1,3 dipolar cycloaddition and then a 1,3 dipolar cycloaddition of the fragments. Fullerene s and carbon nanotube nanotubes can undergo a 1,3 dipolar cycloaddition with an azomethine ylide ... 1,3 Dipolare Cycloaddition nl 1,3 dipolaire cycloadditie ja 1,3 zh 1,3 ... more details
antarafacial geometry required for concerted, thermal 2 2 cycloaddition can be achieved in reactions ... in the cycloaddition product. Electron withdrawing substituents on the ketene and donating substituents ... has allowed access to cycloaddition products in high enantiomeric excess. ref Wynberg, H. Staring ... with ketenes. Examples of all three modes of cycloaddition are discussed in this section. Ketenes ... File KetScope1.png center Ketenes react with alkenes to provide cyclobutanones. If the product of a cycloaddition ... Ketenes undergo 2 2 cycloaddition with ketones and aldehydes to give lactones. Lewis acid catalysis ... accelerate the cycloaddition, they are not of general utility since they also accelerate dimerization .... The success of the reaction is often determined by the relative rates of cycloaddition and dimerization ... more details
Wikify date January 2011 Trimethylenemethane cycloaddition is the formal 3 2 annulation of trimethylenemethane TMM derivatives to two atom pi systems. Although TMM itself is too reactive and unstable to be stored, reagents that can generate TMM or TMM synthons in situ can be used to effect cycloaddition reactions with appropriate acceptors. Generally, electron deficient pi bonds undergo cyclization with TMMs more easily than electron rich pi bonds. ref Yamago, S. Nakamura, E. Org. React. 2003 , 61 , 1. doi http dx.doi.org 10.1002 0471264180.or061.01 10.1002 0471264180.or061.01 ref Introduction Trimethylenemethane is a neutral, four carbon molecule composed of four pi orbitals. Thus, it is a non Kekul molecule that must be expressed either as a biradical or zwitterion. The orbital energy levels of TMM reveal that it possesses singlet and triplet states generally, these two states exhibit different reactivity and selectivity profiles. ref Baseman, R. J. Pratt, D. W. Chow, M. Dowd, P. J. Am. Chem. Soc. 1976 , 98 , 5726. ref Singlet 3 2 cycloaddition, when it is concerted, is believed to proceed under frontier orbital control. When electron rich TMMs are involved, the A orbital serves ... of 3 2 cycloaddition reactions involving this class of intermediates. ref Yamago, S. Nakamura ... be controlled, 3 2 cycloaddition affords isomeric mixtures of methylenecyclopentanes. Three classes ... very high concentrations of alkene must be used or the cycloaddition must be intramolecular. Stereoselectivity ... conditions. For instance, in the presence of an indium co catalyst, the reactive 2 component of the cycloaddition ... in many TMM cycloaddition reactions is a significant advantage of this reaction. For instance, the trans ring junction in TMM cycloaddition adduct 2 was carried through in a synthesis of brefeldin ... with Other Methods Although 1,3 dipolar cycloaddition is a useful method for the generation ... step via annulation. Most of these, like TMM cycloaddition, rely on the generation of a suitable ... more details
The Diazoalkane 1,3 dipolar cycloaddition is a 1,3 dipolar cycloaddition an organic reaction between a 1,3 dipole diazo compounds diazo compound notably diazomethane and a dipolarophile . When the dipolarphile is an alkene , the reaction product is a pyrazoline . ref Advanced organic chemistry reaction mechanisms , Reinhard Br ckner ref The reaction product of a cycloaddition between diazomethane and glutaconic acid trans diethyl glutaconate is a 1 pyrazoline. ref cite doi 10.1016 j.tetlet.2004.04.097 ref This reaction is 100 Regioselectivity regioselective because the diazo terminal nitrogen atom bonds exclusively to the alpha carbon of the ester . The reaction is also a syn addition , and the configuration in the dipolarophile is preserved. The 1 pyrazoline is unstable and isomerization isomerizes to the 2 pyrazoline due to favorable conjugated system conjugation with the ester group. With phenyldiazomethane as the reactant the regioselectivity is reversed and the reaction is extended even further by simple air organic oxidation of the 2 pyrazoline to the pyrazole . File Diazoalkane 1,3 dipolar cycloaddition.svg center Diazoalkane 1,3 dipolar cycloaddition. Another example of a diazo cycloaddition is a diazo thioketone coupling . References Reflist DEFAULTSORT Diazoalkane 1,3 Dipolar Cycloaddition Category Cycloadditions Category Heterocycle forming reactions ar 3,1 ... more details
The Azide Alkyne Huisgen Cycloaddition is a 1,3 dipolar cycloaddition between an azide and a terminal ... reaction . American chemist K. Barry Sharpless has referred to this cycloaddition as the cream of the crop ... 11 2004 AID ANIE2004 3.0.CO 2 5 pmid 11433435 ref Image Huisgen.png center Huisgen 1,3 dipolar cycloaddition ... 3 as a mixture of 1,4 adduct and 1,5 adduct at 98 C in 18 hours. The standard 1,3 cycloaddition ... TBAF Catalyzed 3 2 Cycloaddition of 2 Aryl 1 nitroethenes with TMSN3 under Solvent Free Conditions ... conditions. Copper catalysis A notable variant of the Huisgen 1,3 dipolar cycloaddition is the copper I catalyzed variant, no longer a true concerted cycloaddition, in which organic azides and terminal ... Huisgen Cycloaddition Process Copper I Catalyzed Regioselective Ligation of Azides and Terminal ... dipolar cycloaddition and thus should not be termed a Huisgen cycloaddition. This reaction is better termed the Copper I catalyzed Azide Alkyne Cycloaddition CuAAC . While the reaction can be performed ... center click polymer The copper mediated azide alkyne cycloaddition is receiving widespread ... Cycloaddition and its Application to Polymer Science and Surface Modification author R.A. Evans issue ... solvents, copper I and inert atmospheres to do the cycloaddition with many polymers makes the click label inappropriate for such reactions. An aqueous protocol for performing the cycloaddition with free ... Huisgen 3 2 dipolar cycloaddition reaction author A. J. Dirks, S. S. van Berkel, N. S. Hatzakis ... in the 1970s, which he ran at elevated temperatures. ref 1,3 Dipolar Cycloaddition Chemistry, published ... Wenzel Torn e title Cu Catalyzed Azide Alkyne Cycloaddition year 2008 journal Chemical Reviews ... Accelerated Cu Catalyzed Azide Alkyne Cycloaddition A Mechanistic Report year 2007 journal J. Am ... catalysis The ruthenium catalysed 1,3 dipolar azide alkyne cycloaddition RuAAC gives the 1,5 triazole ... Ruthenium Catalyzed Cycloaddition of Alkynes and Organic Azides year 2005 journal J. Am. Chem. Soc ... more details
Orphan date February 2011 correct title reason bracket 6 4 cycloaddition 6 4 Cycloaddition is a chemical reaction between a six atom pi system and a four atom pi system, leading to a ten membered ring. Because this is a higher order cycloaddition, issues of periselectivity arise in addition to the usual concerns about regio and stereoselectivity. Six atom pi systems that have been employed in the reaction include tropone and tropone derivatives, fulvene s, and cycloheptatriene cobalt complexes. ref Rigby, J. H. Org. React. 1997 , 49 , 331. doi http dx.doi.org 10.1002 0471264180.or049.02 10.1002 0471264180.or049.02 ref Introduction 6 4 Cycloaddition is a thermally allowed, higher order cycloaddition process leading to ten membered rings. Although most linear, acyclic trienes do not give 6 4 products selectively, cyclic trienes give high yields of 6 4 products in many cases. Both cycloheptatrienes and fulvenes can be employed in this reaction, and electron deficient tropone s in particular work well. The pericyclic and transition metal mediated versions of the reaction are stereocomplementary the former gives exo products, and the latter endo products, with essentially complete selectivity in nearly all cases. The possibility of building complex carbocyclic frameworks efficiently has ... and Stereochemistry Metal free reaction The metal free version of the 6 4 cycloaddition takes place ... also has the proper symmetry and orbital coefficients to participate in 6 4 cycloaddition the NHOMO ... reaction The metal promoted 6 4 cycloaddition using a tropone metal complex is a stepwise, photolytic process that lacks the periselectivity issues of the purely thermal 6 4 cycloaddition. The mechanism ..., M. E. Day, C. S. Organometallics 2006 , 25 , 974. ref Scope and Limitations 6 4 Cycloaddition ... 6 4 cycloaddition bicyclo 4.4.1 undecanes and bicyclo 5.3.0 decanes require multiple steps, harsh ... than quartz filtered light. See also 4 3 cycloaddition 4 3 cycloaddition References reflist 2 Category ... more details
correct title reason bracket 4 3 cycloaddition Context date October 2010 4 3 Cycloaddition is the annulation of an allyl or oxyallyl cation with a four atom pi system to form a seven membered ring. It represents one of the relatively few synthetic methods available to form seven membered rings stereoselectively in high yield. ref Rigby, J. H. Pigge, F. C. Org. React. 1997 , 51 , 351. doi http dx.doi.org 10.1002 0471264180.or051.03 10.1002 0471264180.or051.03 ref Introduction Symmetry allowed 4 3 cycloaddition is an attractive method for the formation of historically difficult to access seven membered rings. Neutral dienes and cationic allyl systems most commonly oxyallyl cations may react in a concerted or stepwise fashion to give seven membered rings. A number of dienes have been employed in the reaction, although cyclic, electron rich dienes such as those found in the pyrrole and furan ring systems are the best 4 systems for this process. Intramolecular variants are also efficient. ref Harmata, M. Elahmad, S. Barnes, C. L. Tetrahedron Lett. 1995 , 36 , 1397. ref span style float right padding right 50px padding top 15px 1 span center File 43Gen.png center Recent developments have focused on expanding the scope of enantioselective 4 3 cycloadditions and the range of conditions available for generating the key oxyallyl cation intermediate. Mechanism and Stereochemistry Prevailing ... substitution rather than cycloaddition. ref Henning, R. Hoffmann, H. M. R. Tetrahedron Lett. 1982 , 23 , 2305. ref The cycloaddition itself may be either concerted or stepwise, depending on the nature ... . Stereochemistry Stereochemical control in the 4 3 cycloaddition is not as strict as in the Diels ... of oxyallyl cations for cycloaddition. Reducing agents used include copper bronze ... of a new covalent bond before the cycloaddition itself takes place. These reactions thus .... See also 6 4 cycloaddition 6 4 cycloaddition References reflist 2 DEFAULTSORT 4 3 Cycloaddition ... more details
Orphan date January 2011 In organic chemistry, an intramolecular Diels Alder cycloaddition is a Diels Alder reaction in which the diene and a dienophile are both part of the same molecule. The reaction leads to the formation of one new double bond and two new sigma bonds, but this time the ultimate product is a fused or bridged cyclic ring. Reaction products Because the two reacting groups are already attached, two basic modes of addition are possible in this reaction. Depending on whether the tether that links to the dienophile is attached to the end or the middle of the diene, fused or bridged polycyclic ring systems can be formed. ref M. Nantz, G. Zweifel. Modern Organic Synthesis an Introduction. W.H. 2 Freeman and Company, 2007, pg 429 430 ref The tether than attaches the two reacting groups also affects the geometry of the reaction. As a result of its Conformational isomerism conformational and other structural restrictions, the exo vs endo results ref P.Y Bruice. Organic Chemistry. Pearson Education, Inc. 2007 ref are usually not based on the simple intermolecular Diels Alder reaction effects. Applications Intramolecular Diels Alder reaction Diels Alder cycloaddition is extremely useful for the formation of naturally occurring polycyclic rings. The reaction provides ready access to polycyclic compounds with a great deal of stereoselectivity . The following are several useful drugs whose complete synthesis have been accomplished using the intramolecular Diels Alder reaction. Solanapyrone A Solanapyrone A is an inhibitor of mammalian DNA polymerase and , repair type DNA polymerase. The compound was isolated from the phytopathogenic fungi Alternaria solani , the cause of early blight in tomato and potato plants. The drug is being look as an anti cancer medication. ref B. Lygo, M. Bhatia, J.W.B Cooke, D.J Hirst. Synthesis of solanapyrones A and B. Tetrahedron Letters, 2003 ref Salvinorin A Isolated from the hallucinogenic sage, Salvia Divinorum . Salvinorin A is a potent ... more details
correct title reason bracket Nitrone olefin 3 2 cycloaddition The nitrone olefin 3 2 cycloaddition reaction is the combination of a nitrone with an alkene or alkyne to generate an isoxazoline or isoxazolidine via a 3 2 cycloaddition process. ref Confalone, P. N. Huie, E. M. Org. React. 1988 , 36 , 1. doi http dx.doi.org 10.1002 0471264180.or036.01 10.1002 0471264180.or036.01 ref Introduction When nitrones are combined with either alkenes or alkynes, 3 2 cycloaddition leads to the formation of a new C C bond and a new C O bond. The cycloadditions is stereospecific with respect to the configuration of the alkene however, diastereoselectivity in reactions of C substituted nitrones is often low. ref Tufariello, J. J. Ali, S. A. Klingele. H. O. J. Org. Chem. 1979 , 44 , 4213. ref Regioselectivity is controlled by the dominant frontier orbitals interacting during the reaction, and substrates with electronically distinct substituents tend to react with high regioselectivity. Intramolecular versions of the reaction have been used to synthesize complex polyclic carbon frameworks. Reduction of the N O linkage leads to 1,3 aminoalcohols. span style float right padding right 50px padding top 30px 1 span center File NitrGen.png center Mechanism and Stereochemistry Synthesis of Nitrones Nitrones are generated most often either by the oxidation of hydroxylamines or condensation of monosubstituted hydroxylamines with carbonyl compounds ketones or aldehydes . The most general reagent used for the oxidation of hydroxylamines is mercury II oxide. ref Thesing, J. Sirrenberg, W. Justus Liebigs Ann ... NitrMech3.png center 3 2 Cycloaddition The 3 2 cycloaddition itself is a concerted, pericyclic process ... alkenes is maintained in the products of cycloaddition. Consistent with FMO control of the reaction ... also serve as dipolarophiles in this reaction. The rules for predicting alkene cycloaddition products ... synthesis employing nitrone olefin cycloaddition. ref Dagne, E. Castagnoli, Jr., N. J ... more details
Summary Image by author Licensing PD self date April 2008 Category PD chem Category Classified Chemical Structures Should be SVG chemical Convert to SVG and copy to Wikimedia Commons ... more details
Summary Information Description 4 1 Cycloaddition see Bioorthogonal chemistry Source User Cliu89 Cliu89 User talk Cliu89 talk Special ListFiles Cliu89 Uploads Date Author User Cliu89 Cliu89 User talk Cliu89 talk Special ListFiles Cliu89 Uploads Permission other versions int license Licensing PD self date December 2011 Recreated in chemdraw from 10.1039 C1OB06424J ... more details
The Staudinger synthesis ref cite journal journal Angew. Chem. Int. Ed. doi 10.1002 anie.200702965 pmid 18022986 title Hugo Ugo Schiff, Schiff Bases, and a Century of Lactam Synthesis year 2008 last1 Tidwell first1 Thomas T. volume 47 issue 6 pages 1016 1020 ref , named after the German chemist Hermann Staudinger , is a method to prepare beta lactam lactam s. An imine reacts with a ketene in a formal 2 2 cycloaddition to give the cyclic amide. History The reaction was discovered in 1907 ref cite journal author H. Staudinger journal Justus Liebigs Ann. Chem. year 1907 volume 356 pages 51 123 doi 10.1002 jlac.19073560106 title Zur Kenntniss der Ketene. Diphenylketen ref but did not attract much interest until the 1940s, when the structure of penicillin was elucidated. The lactam moiety of the first synthetic penicillin was constructed using this cycloaddition, ref cite journal author J.C. Sheehan, E.L. Buhle, E.J. Corey , G.D. Laubach, J.J. Ryan journal J. Am. Chem. Soc. year 1950 volume 72 pages 3828 9 doi 10.1021 ja01164a534 issue 8 ref and it remains a valuable tool in synthetic organic chemistry. References references Category Name reactions Category Cycloadditions reaction stub nl Staudinger synthese zh Staudinger ... more details
Image Nitrone general structure 2D.png 150px right thumb General structure of a nitrone A nitrone is the Amine oxide N oxide of an imine and a functional group in organic chemistry . The general structure is R sub 1 sub R sub 2 sub C NR sub 3 sub sup sup O sup sup where R sub 3 sub is different from H. A nitrone is 1,3 dipole in 1,3 dipolar cycloaddition s. It reacts with alkene s to form an isoxazolidine Image Nitrone cycloaddition.png 500px Nitrone cycloadditions One example of this reaction type is the reaction of various Baylis Hillman reaction Baylis Hillman adducts with C Phenyl N methylnitrone forming an isoxazolidine in which R sub 1 sub is phenyl , R sub 2 sub is hydrogen and R sub 3 sub is a methyl group ref Diastereoselectivity of Nitrone 1,3 Dipolar Cycloaddition to Baylis Hillman Adducts Branislav Dugovi , Lubor Fi era, Christian Hametner and Nada Pr nayov c. Arkivoc 2004 BS 834A http www.arkat usa.org home.aspx?VIEW MANUSCRIPT&MSID 877 Article ref . Nitrones react with terminal alkyne s and a copper salt to beta lactam . This reaction is also called The Kinugasa reaction ref The reactions of copper I phenylacetylide with nitrones Manabu Kinugasa and Shizunobu Hashimoto J. Chem. Soc., Chem. Commun., 1972 , 466 467, DOI 10.1039 C39720000466 ref for example in this reaction ref A novel synthesis of lactam fused cyclic enediynes by intramolecular Kinugasa reaction Runa Pal and Amit Basak Chem. Commun. , 2006 , 2992 2994, DOI 10.1039 b605743h ref Image Kinugasa reaction.png 500px center Kinugasa reaction application The first step in this reaction is a dipolar cycloaddition of the nitrone with the in situ generated copper I acetylide to a 5 membered ring structure which rearranges in the second step. References reflist Category Functional groups de Nitrone es Nitrona fr Nitrone nl Nitron ja pl Nitrony pt Nitrona ru zh ... more details
3 2 cycloaddition of nitrones and allenolates David Gonz lez Cruz, David Tejedor, Pedro de Armas, Ezequiel ... ref Image OnWaterReactionApplication.png 400px 3 2 cycloaddition of nitrones and allenolates In this reaction ... 3 2 1,3 dipolar cycloaddition dipolar cycloaddition product then rearranges to a isoxazole ... more details
are replaced by smaller methyl groups. Another example is a photochemical 2 2 cycloaddition with two ... 400px Cycloaddition silicon tether Without the tether, the exo isomer forms. ref Diastereoselective intramolecular photochemical 2 2 cycloaddition reactions of tethered l valinol derived tetrahydrophthalimides ... more details
a highly stereoselective and convergent strategy that involves two important cycloaddition reactions a thermally induced intramolecular 4 2 cycloaddition reaction involving an o quinone and a tetrasubstituted ... 2 2 2 cycloaddition reaction between two acetylenic units. ref name Nicolaou Nicolaou, K ... more details
pdf Cycloaddition mechanism and the solvent dependence of rate Pure & Appl. Chem. 1980, Vol.52, pp.2283 ... Dipolar cycloaddition s. Also 1,4 dipolars ref name Takahisa , 1,5 dipolars, etcetera exist. Examples ... See also Zwitterion Ylide 1,3 dipole 1,3 Dipolar cycloaddition Betaine References references Category ... more details
Image Azoxy group 2D.png thumb right 150px The structure of the azoxy functional group, where R is a substituent . Image Azoxybenzene 2D skeletal.png thumb right 150px Azoxybenzene diphenyldiazene oxide , an example of an azoxy compound. Azoxy compounds are a group of chemical compound s sharing a common functional group with the general structure RN N sup sup O sup sup R. ref GoldBookRef file A00567 title azoxy compounds ref They are considered Amine oxide N oxides of azo compound s. Azoxy compounds are 1,3 dipole s. They give 1,3 dipolar cycloaddition with double bonds. Azoxy compounds are suspected to be genotoxic. References Reflist Guideline On The Limits Of Genotoxic Impurities http www.emea.eu.int pdfs human swp 519902en.pdf Category functional groups fr Azoxy nl Azoxyverbinding ja zh ... more details
The DeMayo reaction is a photochemical reaction in which the enol of a 1,3 diketone reacts with an alkene or another species with a C C bond and the resulting cyclobutane ring undergoes a retro aldol reaction to yield a 1,5 diketone ref Li, Jie Jack. Named Reactions A Collection of Detailed Reaction Mechanisms. Springer 2003, p. 105. ref Image Demayo reaction.png The DeMayo reaction The net effect is to add the two carbon atoms in the C C double bond between the two carbonyl groups of the diketone. It is thus useful in syntheses both as a relatively selective way to join two parts of a molecule and as a way to apply the more developed chemistry of 1,3 diketone synthesis to 1,5 diketones. The first part is a 2 2 cycloaddition . The ensuing retro aldol cleavage is favored by the relative instability of the cyclobutane ring. External links 1. Some background and examples http rawalgroup.uchicago.edu litmeetings demayo.htm Link References Reflist Category Organic reactions ... more details
distinguish Annulment Annulation derived from annulus mathematics annular , occasionally annelation in organic chemistry is a chemical reaction in which a new ring is constructed on another molecule often another ring . ref GoldBookRef title annulation url http goldbook.iupac.org A00367.html GoldBookRef title annelation url http goldbook.iupac.org A00365.html ref Image AnnulationStrategies.png 400px Annulation A intramolecular ring closing B transannulation C cycloaddition Examples are the Robinson annulation , Danheiser annulation and certain cycloaddition s. Annular molecules are constructed from side on condensed cyclic segments, for example helicene s and acene s. In transannulation a bicyclic molecule is created by intramolecular carbon carbon bond formation in a large monocyclic ring. An example is the samarium II iodide induced ketone alkene cyclization of 5 methylenecyclooctanone which proceeds through a ketyl intermediate ref Construction of Bicyclic Ring Systems via a Transannular SmI2 Mediated Ketone Olefin Cyclization Strategy Gary A. Molander, Barbara Czak , and Michael Rheam J. Org. Chem. 2007 72 5 pp 1755 1764 Article DOI 10.1021 jo062292d ref Image KetoneOlefinCyclization.png 400px Ketone olefin cyclization Benzannulation The term benzannulated compounds refers to derivatives of cyclic compound s usually aromatic which are fused to a benzene ring. Examples are listed in the table below class wikitable style text align center Benzannulated derivative Source of cyclic compound Benzopyrene Pyrene Quinoline rowspan 2 Pyridine Isoquinoline Chromene rowspan 2 Pyran Isochromene Indole rowspan 2 Pyrrole Isoindole Benzofuran rowspan 2 Furan Isobenzofuran Benzimidazole Imidazole Transannular interaction A transannular interaction in chemistry is any chemical interaction favorable or nonfavorable between different chemical bond non bonding molecule molecular functional group groups in a large ring or macrocycle ref Experimental evidence in support of transannul ... more details
The Ojima lactam is an organic compound of some importance in the commercial production of Taxol total synthesis Taxol . This lactam was first synthesized by Iwao Ojima ref cite journal title New and efficient approaches to the semisynthesis of taxol and its C 13 side chain analogs by means of lactam synthon method author Iwao Ojima, Ivan Habus, Mangzhu Zhao, Martine Zucco, Young Hoon Park, Chung Ming Sun and Thierry Brigaud journal Tetrahedron journal Tetrahedron volume 48 issue 34 year 1992 pages 6985 7012 doi 10.1016 S0040 4020 01 91210 4 ref . The organic synthesis is an illustration of asymmetric synthesis via a chiral auxiliary . The reaction centers around an imine lithium enolate cycloaddition . In order to ensure the correct stereochemistry the phenyl group and the silyl ether must adopt a cis configuration in the lactam lactam a chiral auxiliary is used in the enolate synthesis. The enolate synthesis starts from glycolic acid . The hydroxyl group is protected by a benzyl group and the carboxylic acid is activated by reaction with thionyl chloride to the acid chloride . The acid chloride reacts with the chiral auxiliary trans 2 phenyl 1 cyclohexanol . The benzyl group is then removed and replaced by a TES silyl ether by reaction with triethylsilyl chloride . Reaction with organolithium reagent phenyllithium affords the enolate . Image OjimaTailPartI.svg center 600px Ojima lactam I The imine synthesis is a reaction of Silazane hexamethylene silazane with phenyllithium to a strong amide base followed by a condensation reaction with benzaldehyde . Image OjimaLactamPartII.svg center 500px Ojima lactam II Both imine and enole intermediate join in a cycloaddition reaction followed by an intramolecular nucleophilic acyl substitution of the amine with expulsion of the chiral auxiliary to the cis isomer cis lactam . The triethylsilyl group is removed by hydrogen fluoride and the benzoyl group is added in a Schotten Baumann reaction . Image OjimaLactamPartIII.svg c ... more details
reactions have been identified which fit the concept better than others 3 2 cycloaddition s, such as the Huisgen 1,3 dipolar cycloaddition , in particular the Cu I catalyzed stepwise variant, ref cite journal author Spiteri, Christian and Moses, John E. title Copper Catalyzed Azide Alkyne Cycloaddition ... 2297 2299 doi 10.1021 bc8004446 ref 4 1 cycloaddition s between isonitriles isocyanides and tetrazines ... yne reaction . Azide alkyne Huisgen cycloaddition main Azide alkyne Huisgen cycloaddition One of the most popular reactions within the click chemistry concept is the azide alkyne Huisgen cycloaddition ... V. Sharpless, K. Barry title A Stepwise Huisgen Cycloaddition Process Copper I Catalyzed Regioselective ... Cycloaddition Scope and Mechanism year 2008 journal Journal of the American Chemical Society volume ... more details
Infobox scientist name Rolf Huisgen image Rolf Huisgen and Franz Marc s Mandrill.JPG image size alt caption Rolf Huisgen 2004 in front of the painting Mandrill from Franz Marc birth date birth date and age 1920 06 13 df yes birth place Gerolstein , Rhineland Palatinate , Germany death date death place nationality Germany German field Chemist work institution University of Munich alma mater University of Munich doctoral advisor Heinrich Otto Wieland known for 1,3 Dipolar cycloaddition prizes 1961 Liebig Medal Rolf Huisgen born 13 June 1920 is a German chemist. He was born in Gerolstein and studied in Munich under the supervision of Heinrich Otto Wieland . After completing his Ph.D. in 1943 and his habilitation in 1947, he became professor at the University of T bingen in 1949. He came back to the University of Munich in 1952 where he stayed dedicated to the research long after his emeritation in 1988. ref cite journal title Rolf Huisgen A Gentleman Scholar with Energy and Passion author Jeffrey I. Seeman journal Helvetica Chimica Acta volume 88 issue 6 pages 1145 1153 year 2005 doi 10.1002 hlca.200590097 ref Besides his 1,3 Dipolar cycloaddition , which are also known as the Huisgen cycloaddition or Huisgen reaction , ref cite journal title Kinetics and Mechanism of 1,3 Dipolar Cycloadditions first Rolf last Huisgen journal Angewandte Chemie International Edition volume 2 issue 11 date November 1963 pages 633 645 url http www3.interscience.wiley.com cgi bin abstract 106572717 ABSTRACT doi 10.1002 anie.196306331 ref ref cite journal title 1,3 Dipolar Cycloadditions. Past and Future first Rolf last Huisgen journal Angewandte Chemie International Edition volume 2 issue 10 date October 1963 pages 565 598 url http www3.interscience.wiley.com cgi bin abstract 106572678 ABSTRACT doi 10.1002 anie.196305651 ref he had a big influence on chemistry departments in Germany and Austria, due to his large number of habilitants becoming professors. Ivar Ugi , Johann Mulzer , Bernd Gi ... more details
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