Maria de la Concepcion Foces-Foces

One-pot synthesis of a new class of fused 2,4-diimino-1,3-diazetidines by an aza-Wittig/[2 + 2] cycloaddition of carbodiimides process

The new [5.7.4]tricyclic ring system 3 is synthesized in a one-pot reaction from bis(iminophosphorane)1 and two equivalents of aryl isocyanate; compound 1 also reacts with one equivalent of isocyanate to give the bicyclic [1,3]diazepine 6; the crystal structure of compounds 3 and 6 are determined.

Reactivity and chemoselectivity of primary Z-β-enamino-λ5-phosphazenes towards electrophiles

The multifunctional character of Z-β-enamino-λ5-phosphazenes (2) towards several electrophiles is shown. Thus, while hydrogen or alkyl halides react through the PN double bond, affording β-enaminophosphonium salts (3) and (4), in the presence of a base, alkylation of the enamine moiety (6) occurs. Ethyl chloroformate acts as acylating agent of the enaminic nitrogen and with bromine and triethylamine, α-bromoenaminophosphazenes (8) are obtained.

Structure of 1-(1-adamantyl)pyrazoles: crystal geometry and carbon-13 NMR spectroscopy

Abstract Crystal structures of 1-(1-adamantyl)pyrazole, 1a, and 1-(1-adamantyl-3-ol)-4-nitropyrazole, 2a, have been solved by X-ray analysis. The space groups and cell parameters are P21, a, 7.4021(3), b, 10.7529(5),c, 6.9651(2)A, β, 90.206(3)° for 1a with Z = 2 and P2/n, a, 31.1172(14), b, 6.8506(1), c, 12.0313(3)A, β 94.873(3)° for 2a with Z = 8. Refinements were carried out down to R values of 0.043 (Rw, = 0.046) and 0.079 (Rw = 0.061) for the 951 (2σ(I)) and 2461 (3σ(I)) observed reflections respectively. The conformation about the bond between the heterocycle and the carbocycle is discussed on theoretical grounds INDO calculations): the adamantane behaves as a free rotor. The stcricinteractions of the adamantyl residue with the methyl substituents in 2- and 5-position of pyrazole are apparent in the C-13 chemical shifts.