Reaction of diphenylketene (I) with azadienes (II-IX), having -C=N-C=N- multiple bond system between carbon-nitrogen double bond in heterocycles and their side-chain carbon-nitrogen double bond, gave the 1, 4-cycloadducts (XI-XVIII), respectively. Hydrogenolysis of the 1, 4-cycloadducts (XIb, XIIb, and XVIb), with lithium aluminum hydride in tetrahydrofuran gave the 1-propanol derivatives (XIX, XXI, and XXII), respectively. On the other hand, reaction of I with 3-(p-anisylideneamino)-5-phenylisoxazole (Xb) and 2-benzylideneaminopyridine (XXIV) respectively afforded 1-[3-(5-phenylisoxazolyl)]-3, 3-diphenyl-4-(p-anisyl)-2-azetidinone (XXIII) and 1-(2-pyridyl)-3, 3, 4-triphenyl-2-azetidinone (XXV).
Reaction of the conjugated 1, 2-diimines with isocyanates was investigated. 6, 6', 7, 7'-Tetramethoxy-3, 3', 4, 4'-tetrahydro-1, 1'-biisoquinoline (I) reacted with several phenyl isocyanates (Ila-e) and benzoyl isocyanate (IIf), giving criss-cross type 1 : 2-adducts (IIIa-f). Behavior of N, N'-bis(cyclohexyl)ethylenediimine (VII) was different depending on reaction conditions. Reaction of VII with IIf at room temperature afforded 1 : 2-adduct (VIII) through 1, 2-cycloaddition to C=N bond of VII, presumably due to the contribution of 1, 4-dipolar structure of IIf, while in boiling xylene gave criss-cross type 1 : 2-adduct (X). On the other hand, although addition of N, N'-bis(cyclohexyl)butylene-2, 3-diimine (XV) to IIf was not found to take place at room temperature, XV reacted with IIf in boiling xylene to give a criss-cross adduct (XVI) as VII.
1-(1-Pyrrolidinyl) cyclohexene reacts with 2-(p-nitrobenzylideneamino) benzoxazole and 2-(p-nitrobenzylideneamino) benzimidazole, affording new Diels-Alder type adducts respectively.
The reactions of diketene with S, S-dimethyl-N-2-pyridinylsulfilimine (IVa) and N-2-benzothiazolyl-S, S-dimethylsulfilimine (IVb) gave 2-(2-dimethylsulfuranylideneaceto-acetamido) pyridine (VIa) and 2-(2-dimethylsulfuranylideneacetoacetamido) benzothiazole (VIb), respectively. However, the reaction of diketene with S, S-dimethyl-N-(4-nitrophenyl) sulfilimine (IVc) and N-2-benzoxazolyl-S, S-dimethylsulfilimine (IVd) gave 3-acetyl-4-hydroxy-6-methyl-1-(4-nitrophenyl)-2-pyridone (VIIc) and 3-acetyl-1-(2-benzoxazolyl)-4-hydroxy-6-methyl-2-pyridone (VIId), respectively. On the other hand, the reaction of diphenylketene with sulfilimines (IVa, IVb, and IVd) gave the corresponding 1, 3-cyclization products (VIII, IX, and X).
Abstract Die Benzyliden‐2‐amino‐benzox‐ bzw. benzimidazole (Ia) und (Ib) reagieren mit dem Enamin (II) über diskutierte Zwischenstufen zu 1,4‐Addukten (III).
Reaction of several conjugated C-N double bond compounds with diketene was carried out with a view to establishing the structure-reactivity relationship of the 1, 3-diaza-1, 3-butadiene system. Formamidine derivatives (IIIa-h) reacted with diketene in benzene to form the products (Va-h) through 1, 4-dipolar cycloaddition with the elimination of dimethylamine, respectively. Similarly, reaction of diketene with 2-(p-dimethylaminobenzylideneamino) benzothiazole (IXa) and 2-(p-dimethylaminobenzylideneamino) benzimidazole (IXb) respectively afforded 3-acetyl-2-(p-dimethylaminophenyl)-2, 3-dihydro-4-oxo-4H-pyrimido [2, 1-b] benzothiazole (Xa) and 3-acetyl-2-(p-dimethylaminophenyl)-2, 3-dihydro-4-oxo-4H-pyrimido-[1, 2-a] benzimidazole (Xb).
