Fused indoles. 2. Synthesis and reactions of imidazo[1,2‐ a ]‐ and pyrimido[1,2‐ a ]‐indoles

The alkylation of 2‐chloroindole‐3‐carboxaldehyde ( 1 ) and 3‐acetyl‐2‐chloroindole ( 5 ) with 3‐chloro‐ N,N ‐dimethyl‐1‐propylamine, 3‐chloro‐ N,N ‐diethyl‐1‐propylamine and 2‐chloro‐ N,N ‐dimethyl‐1‐ethylamine is described. Following alkylation, demethylation occurs and furnishes imidazo[1,2,‐ a ]‐ and pyrimido[1,2‐ a ]indoles ( 3a,6,8,10 ). Pyrimido‐indole 3a , on treatment with lithium aluminum hydride, furnishes the bis‐indole 12 . Analogous reaction with diborane affords the reduced product 14 , while reaction with methyllithium yields the deformylated product 13 . Spectral data of the resulting compounds are also discussed.