Pyrazolo azocines

Ninhydrin (858) reacts with p-cresol in the presence of zinc chloride to yield the eight-membered lactone (859). Generation of the carbene (860) from the corresponding diazopyrazole in the presence of benzene derivatives PhR (R = MeO, Me, Cl, CN, or NO2) results in mixtures of isomeric substitution products (861) and ring-expanded pyrazolo-azocines (862) electron-withdrawing substituents enhance the formation of the latter cf. p. 158). The oxadiazoloben-zodiazocinone (864) is formed by the action of phosgene on the iV-oxide (863). ... 

An azocine ring is seldom formed in carbene reactions. In addition to the above-mentioned formation of azocines 164 (n = 3) and 68 (n = 4), the conversions of benzenes by 5-ferf-butyl-3//-pyrazolidene (193) to pyrazolo[l,5-a]azocines 194, have been reported—the highest yield (40%) being attained with nitrobenzene (79TL4697). 

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