1,2-Cycloaddition of αβ-unsaturated esters to a biased enamine. Crystal and molecular structure of a cis-bicyclo[4.2.0]octane derivative

Abstract

The reactions of 1-morpholino-4-t-butylcyclohexene with diethyl maleate and diethyl fumarate are reported. The configurational aspects of the bicyclo[4.2.0]octane obtained under mild reaction conditions, are examined on the basis of its X-ray analysis. The crystal structure has been determined by direct methods and refined by block-diagonal matrix least squares to R 0.057. Crystals are monoclinic, space group P2₁/n, with Z= 4 in a cell with dimensions a= 13.01(1), b= 14.06(1), c= 12.61(1)Å, β= 103.4°. The cyclohexane and the cyclobutane rings are cis-fused and the two adjacent ethoxycarbonyl groups are mutually trans.