Construction of polycyclic compounds by cyclocarbonylation. 6. Palladium-catalyzed cyclocarbonylation of 3-(heteroaryl)allyl acetates
摘要:
Acetoxybenzofurans, acetoxybenzothiophenes, acetoxyindoles, and acetoxycarbazoles were obtained in high yields by cyclocarbonylation of 3-furyl-, 3-thienyl-, 3-pyrrolyl-, and 3-indolylallyl acetates, respectively, in the presence of Ac2O, NEt3, and a catalytic amount of PdCl2(PPh3)2 at 130-170-degrees-C under 50-70 atm of CO. 3-(3-Furyl)allyl and 3-(3-thienyl)allyl acetates cyclized selectively at the 2-position of the heterocyclic nucleus to give 7-acetoxybenzofuran and 7-acetoxybenzothiophene, respectively. The synthetic utility of the reaction was demonstrated by the synthesis of cannabifuran from isothymol.
stereodivergent Pd/Cu catalyst system has been developed for the unprecedented dynamickineticasymmetrictransformation (DyKAT) of racemic unsymmetrical 1,3-disubstituted allylic acetates with prochiral aldimine esters. A series of α,α-disubstituted α-amino acids bearing vicinal stereocenters were easily prepared with excellent enantioselectivities (up to >99% ee) and diastereoselectivities (up to >20:1 dr). By
Radical reactions in esters with alkoxy functionality chemistry an unusual alcohol moiety hydrogen abstraction
作者:Ming-Chung Yan、Yeong-Jiunn Jang、Jhenyi Wu、Yung-Feng Lin、Ching-Fa Yao
DOI:10.1016/j.tetlet.2004.02.158
日期:2004.4
Various geometrically pure (E)-alkenes have been synthesized by radical substitution of alcohol moieties generated via hydrogenabstraction within ethyl esters. These reactions occurred with high regioselectivity and gave a new access to 1-methyl-3-aryl-allyl esters.