Synthesis of indole oxazolines; novel 5-HT3 antagonists

Abstract

The synthesis of a novel series of spiro fused indole oxazolines is reported, the spiro centre being generated via addition of an azabicyclic amino alcohol to an indole imidate. The azabicyclic amino alcohol was generated from the corresponding cyanohydrin by borane reduction, which also served to protect the highly nucleophilic azabicyclic nitrogen. In the case of the unsymmetrical azabicyclic system 10, stereocontrolled cyanohydrin formation was achieved. Selective alkylation of the indole nitrogen was facilitated by borane protection of the azabicyclic nitrogen.