13C-13C spin-spin coupling constants in structural studies: XLIII. Stereochemical study on functionalized 3-iminopyrrolizines
摘要:
Three 1-ethylsulfanyl-3-imino-3H-pyrrolizine-2-carboxamides were synthesized by intramolecular cyclization of substituted (2Z)-2-cyano-3-ethylsulfanyl-3-(1H-pyrrol-2-yl)prop-2-enamides. The products were assigned syn configuration at the C = N bond and preferential s-cis orientation of the carbamoyl group on the basis of the experimental C-13-C-13 coupling constants and high-level nonempirical quantum-chemical calculations.
Synthesis of 3- and 5-amino-5-(3)-(pyrrol-2-yl)isoxazoles
作者:Lyubov' N. Sobenina、Vladislav N. Drichkov、Al'bina I. Mikhaleva、Olga V. Petrova、Igor A. Ushakov、Boris A. Trofimov
DOI:10.1016/j.tet.2005.03.031
日期:2005.5
5-Amino-3-(pyrrol-2-yl)isoxazoles were selectively prepared by the reaction of 2-(2,2-dicyano-1-ethylthioethenyl)pyrroles with hydroxylamine in methanol. Under analogous conditions, 2-(2-carbamoyl-2-cyano-1-ethylthioethenyl) pyrroles with hydroxylamine gave 5-aminoisoxazoles and their structural isomers, 3-aminoisoxazoles (3–5% yield). The latter were selectively prepared by reacting 2-(2-carbamoy