AlCl3-promoted [3+2] annulation of cis-2,3-disubstituted cyclopropane 1,1-diesters with isothiocyanates: stereoselective synthesis of densely substituted 2-iminodihydrothiophenes

cis-2,3-Disubstituted cyclopropane 1,1-diesters were found to be much more reactive than their corresponding trans-isomers in the AlCl3-promoted [3 + 2]-annulations with isothiocyanates. The reaction with the cis-cyclopropanes proceeded to completion within minutes, providing a variety of densely substituted diastereomerically pure 2-iminodihydrothiophenes in moderate to excellent yields.