AbstractThe reaction of nucleophilic and non‐nucleophilic bases wtih 2‐carbamoyl‐3‐(γ‐chloropropyl)‐1‐indenone (5) have been investigated. Condensation of γ‐chlorobutyrophenone with malono‐nitrile afforded α‐cyano‐β‐(3‐ehloropropyl)cinnamonitrile which was cyclized in concentrated sulfurie acid to produce 5. Two other products obtained from the cyclization reaction were 2‐carbamoyl‐3‐(γ‐ehloropropylidene)‐1‐indanone (4) and α‐carbamoyl‐β‐(3‐chloropropyl)cinnam‐amide.Treatment of a solution of 4 in ethyl acetate with piperidine resulted in cyclization of the γ‐chloropropyl side chain to give 2‐carbamoyl‐3‐cycIopropyl‐1‐indanone. The same compound was obtained in improved yield by the treatment of 4 or 5 with sodium hydroxide solution. The reaction of dirnethylamine with 5 in benzene gave initial Michael addition of the amine followed by internal alkylation of the carbanion so formed to yield 3a‐dimethylamino‐2,3,3a,8‐tetrahydro‐8‐oxoeyclopent[a]indene‐8a(lH)earboxamide (7a). Similarly addition of ammonia, pyrrolidine, piperidine, benzenethiol, p‐toluenethiol, 2‐naphthalenethiol and nitromethane to the indenone I gave respective analogs of type 7.Treatment of 5 with sodium cyanide in aqueous t‐butyl alcohol resulted in a similar Michael addition followed by internal alkylation. In addition, cyclization between the nitrile and the carbamoyl functions occurred in the same step to give 2‐oxo‐4‐imino‐7,8‐benzo‐3‐aza[3.3.3]‐propellan‐6‐one (13a). Hydrolysis of the iminopyrrolido ring in 13a to the corresponding suecin‐irnide gave 2,4‐dioxo‐7,8‐benzo‐3‐aza[3.3.3]propellan‐6‐one (13b). Reactión of 13b with methyl iodide, allyl bromide, benzyl bromide, and diethyluminoethyl chloride afforded the corresponding N‐alkylated products. A similar sequence starling with δ‐ehlorovalerophenone led to 5,6‐fused ring systems, including a [4.3.3]propellane. 2,9‐Dioxo‐4‐methyl‐7,8‐benzo‐3‐aza[4.3.3]propell‐4‐ene was obtained by the reaction of 5 with acetone in dilute alkali.