Benzodiazocine-dione

Benzodiazocine and dibenzo[Z>,/][ 1,4]diazocine-diones (220) and (218) are obtained by condensation of diethyl succinate and phthalate, respectively, with o-phenylenediamine (69JOC2138). Contrary to an early report, the use of phthaloyl chloride leads to other products and not the tricyclic diazocine. The dibenzo derivative is also formed in the oxidation of diazabiphenylene (219) (78T495). Ring contraction of (218) occurs readily on heating or on treatment with PCI5 or with base. 

Carbon suboxide <920485> and malonyl dichloride <90EGP275677> react with o-aminobenzyl amines to afford benzodiazocin-2,4-diones (22) (Equation (9)) and (50 R = Me, Ph) (Equation (10)), respectively, in moderate yield. 

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