Chloroformate ester-induced reductive 1,2-bond cleavage of some 1,2,3,4-tetrahydro-β-carboline derivatives

Abstract

Treatment with a chloroformate ester at –70 °C and subsequent reaction with NaBH₃CN converts 1,2,5,6,11,11b-hexahydro-3H-indolo[3,2-g]indolizine and derivatives of 1,2,3,4,6,7,12,12b-octahydroindolo[2,3-a]-quinolizine cleanly into the corresponding C/D ring-cleaved urethane derivatives; when the order of addition of reagents is reversed in experiments performed at 0 °C, formation of stable substrate–cyanoborane adducts competes with this reaction.