Enhanced formation of inverted housane through steric effects by rotationally unsymmetric bridgehead substituents in the ring closure of triplet cyclopentane-1,3-diyl diradicals, generated photolytically from 2,3-diazabicyclo[2.2.1]heptene(DBH)-type azoalkanes†
Abstract
The photolysis of the cyclopentene-annelated DBH-type azoalkanes 1c,d with the n-propyl and acetoxymethyl substituents at the bridgehead positions affords under singlet conditions (high-temperature direct photolysis) predominantly the retained housanes anti-2c,d, while under triplet conditions (low-temperature direct or