Intramolecular Cycloaddition of Geminal Dichloroazomethine Ylides to Multiple Carbon-Carbon Bonds

Geminal dichloroazomethine ylides generated by reaction of dichlorocarbene with Schiff bases derived from O-alkenyl- or O-alkynylsalicylaldehyde undergo intramolecular [3 + 2]-cycloaddition with participation of the olefinic or acetylenic dipolarophile to afford chromeno[4,3-b]pyrrole and chromeno[4,3-b]pyridine derivatives. The greatest yields of the intramolecular cycloaddition products were obtained from N-methyl-substituted dichloroazomethine ylides, whereas the main stabilization path of N-phenyl and N-tert-butyl derivatives was cyclization to geminal dichloroaziridines.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 4, 2005, pp. 571–577.Original Russian Text Copyright © 2005 by Khlebnikov, Voznyi, Novikov, Kostikov.