Synthesis of Phenyl‐ and Benzyl‐Substituted Pyrrolidines and of a Piperidine by Intramolecular C ‐Alkylation. Synthons for tricyclic skeletons

The construction of new or novelly functionalized annulated and bridged tricylic compounds by two consecutive C,C‐bond formations (a and b in la , Scheme 1 ) is described. In a first step, chloroalkyl‐substituted aminonitriles yielded pyrrolidines 8 , 15a , 15b , 23 , 25 and piperidine 18 by carbanionic ring closure ( Schemes 5, 6, 7 and 8 ). Subsequent Friedel‐Crafts cyclization transformed the β‐aminonitriles 8 , 15a , 15b , and 18 either directly or via their carboxylic acid derivatives to the indeno [ 1, 2 ‐c] pyrrole , 2 , 5 ‐ methano ‐ 3 ‐ benzazocine , benz [ f ] isoindoline and 1 , 4 ‐ ethano ‐ 2 ‐ benzazapine skeletons 11 , 16a , 16b and 21 , respectively ( Schemes 5, 6 and 7 ). By classical ring expansion reactions the pyrrolo [ 3 , 4 ‐ c ] isoquinoline and benzopyrano ‐[ 3 , 4 ‐c] pyrrole skeletons 28 resp. 31 were obtained from 11 ( Scheme 9 ).