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Oxidation of 1‐methyl‐3‐methoxycarbonyl‐β‐carboline with selenium dioxide gave 1‐formyl‐3‐methoxycarbonyl‐β‐carboline II. Compound II reacted with acetic or propionic anhydride to give easily the 2‐methoxycarbonyl‐6H‐indolo[3,2,1‐d,e][1,5]naphthyridin‐6‐ones III; reaction of II with some primary amines led to the formation of the Schiff bases IV, which were reduced to the 1‐aminomethyl‐3‐methoxycarbonyl‐β‐carbolines V with sodium borohydride. Cyclization of V with aqueous formaldehyde led to the pyrimido[3,4,5‐lm]pyrido[3,4‐b]indoles VI. Analogously, cyclization with formaldehyde, acetone or 1,1′‐carbonyldiimidazole of the 3‐aminomethyl‐ 1,2,3,4‐tetrahydro‐β‐carbolines VIII, obtained by reaction of 3‐methoxycarbonyl‐1,2,3,4‐tetrahydro‐β‐carboline VII with amines followed by lithium aluminium hydride reduction of the resulting amides, gave the imidazo[1′,5′‐1,6]pyrido[3,4‐b]indoles IX and X. Dieckmann cyclization of 3‐methoxycarbonyl‐2‐[(3‐ethoxycarbonyl)‐1‐propyl]‐1,2,3,4‐tetrahydro‐β‐carboline XI led to a 1:1 mixture of the β‐ketoesters XII and XIII, which underwent deethoxycarbonylation to 5,6,8,9,10,11,11a,12‐octahydroindolo[3,2‐b]quinolizin‐11‐one XIV. Finally, the polyphosphoric acid (or esters) catalyzed cyclization of the N‐acyl derivatives XVI of 3‐hydrazinocarbonyl‐β‐carboline XV led smoothly to the 3‐(1,3,4‐oxadiazol‐2‐yl)‐β‐carbolines XVII.

While 2‐acetyl and 2‐benzoyl‐3‐aminobenzofurans did not react with hydrazine, monomethyl‐ and N,N‐dimethylhydrazine to give the related hydrazones, their 3‐N‐(p‐toluenesulfonyl) derivatives afforded them smoothly in good yields. Depending upon reaction conditions, products arising from hydrazone cyclization to benzofuropyrazoles and/or from furan ring cleavage at the C2O bond to give 5‐(2‐hydroxyphenyl)pyrazoles were also formed. The formation of these products depends upon hydrazones configuration and is discussed. Only (E)‐isomers appear to undergo furan ring opening. In acidic media at room temprature either the hydrazones or the monomethylhydrazones gave the same related α‐azines. Microanalyses, ir, uv, 1H‐nmr and ms spectra are in agreement with the proposed structures.

Methoxyphenyldiazaadamantanones and -ols 1293 (2.4 g.) and triethylamine (3.6 g.). The free base was a yellow oil, yield 4.3 g. (93%).