The first [2.2]cyclophane with free N–H in the bridge

Abstract

The synthesis, absolute configuration, chiroptical properties and hydrogen bonding of the helical-chiral title compound 1 are reported, which is the first strained [2.2]phane that has an unsubstituted nitrogen in the bridge; an X-ray structure analysis shows 1 to crystallise spontaneously enantiomerically pure, and the presence of the sulfure atom allowed the determination of the absolute configuration of the (–)-enantiomer to be established as a left-handed (M) helix.