New Tandem Reactions of Metal Carbenoids. Intermolecular Formation of Azomethine Ylide from Methyl 2-Diazo-2-phenylacetate and Schiff Base: Intramolecular 1,3-Dipolar Cycloaddition |
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Authors: | A F Khlebnikov M S Novikov A A Bespokoev R R Kostikov J Kopf Z A Starikova M Yu Antipin |
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Institution: | (1) St. Petersburg State University, Universitetskii pr. 26, St. Petersburg, 198504, Russia;(2) Institut fur Anorganische Chemie, Martin-Luther-King-Platz 6, D-20146 Hamburg, Germany;(3) Nesmeyanov Institute of Organometallic Compounds, Russian Academy of Sciences, Moscow, Russia |
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Abstract: | Rhodium acetate-catalyzed decomposition of methyl 2-diazo-2-phenylacetate in the presence of substituted N-methylbenzylideneamines possessing an activated alkenyl fragment (dipolarophile) in the side chain gives products of intramolecular cycloaddition of intermediate Z,E- and E,Z-azomethine ylides. The cycloaddition is regioselective, and the products are hexahydrochromeno4,3-b]pyrrole derivatives. The stereoselectivity of the process depends on the temperature. In the temperature range from 20 to 80°C, the major stereoisomer is that with cis junction of the tetrahydropyran and pyrrolidine rings. N-Phenylazomethine ylides generated from methyl 2-diazo-2-phenylacetate and alkyl 4-2-(phenyliminomethyl)phenoxy]-2-butenoates at 40°C undergo cyclization to aziridines at a higher rate, as compared to the rate of cycloaddition to the internal dipolarophile. N-Phenylazomethine ylides generated by thermolysis of the corresponding aziridine or by the “deprotonation” method react with equal regio- and stereoselectivity to give intramolecular cycloaddition products, hexahydrochromeno4,3-b]pyrrole derivatives with trans-fused tetrahydropyran and pyrrolidine rings. Analysis of the experimental and calculation data suggests preference of the endo transition state in the cycloaddition of the examined azomethine ylides.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 6, 2005, pp. 939–949.Original Russian Text Copyright © 2005 by Khlebnikov, Novikov, Bespokoev, Kostikov, Kopf, Starikova, Antipin. |
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