Derivatives of the Benzo[5,6]cyclohepta[1,2,3-Cd]thieno[3,2-C]pyridine System. X-Ray Crystal Structure of 8,9-Dimethoxy-1,2,3,6,11,11a-hexahydrobenzo[5,6]cyclohepta[1,2,3-Cd]thieno[3,2-C]pyridine-1-carbonitrile

Abstract

During attempts to prepare 9,10-dimethoxy-4,7,12,12a-tetrahydro-5H- benzo [g] thieno [3,2-a] quinolizine (1), and subsequent cyanogen bromide- induced ring cleavage of this tetracyclic base, two by-products were isolated. The preparations of these two compounds are described, and their structures elucidated as 8,9-dimethoxy-1,2,3,6,11,11a-hexahydrobenzo [5,6] cyclohepta [1,2,3-cd] thieno [3,2-c]pyridine (5a), and its 1-carbonitrile derivative (5b). An N-methyl derivative (5c) has been prepared from (5a). These products (5) are the first examples of a new heterocyclic system. The crystal and molecular structure of the cyanamide (5b) has been determined by X-ray crystallographic methods.