P. Sabatino

Structure and molecular orbital study of ergoline derivatives: 1-(6-methyl-8β-ergolinylmethyl)imidazolidine-2,4-dione (I) and 2-(10-methoxy-1,6-dimethyl-8β-ergolinyl)ethyl 3,5-dimethyl-1H-2-pyrrolecarboxylate toluene hemisolvate (II) and comparison with nicergoline (III)

(I): C19H22N4O2 (Registry No. 95688-34-9), m.p. greater than 573 K, Mr = 338.4, orthorhombic, P2(1)2(1)2(1), a = 8.392 (2), b = 13.004 (2), c = 15.676 (5) A, V = 1710.7 (7) A3, Z = 4, Dx = 1.31 Mg m-3, Mo Ka radiation, lambda = 0.71069 A, mu = 0.08 mm-1, F(000) = 720, T = 293 K, final R = 0.051 for 990 independent reflexions. (II): C26H33N3O3.1/2C7H8 (Registry No. 54370-23-9), m.p. 427-429 K, Mr = 481.64, monoclinic, P2(1), a = 11.595 (4), b = 14.274 (2), c = 16.103 (4) A, beta = 100.19 (3) degrees, V = 2623 (1) A3, Z = 4, Dx = 1.22 Mg m-3, Mo Ka radiation, lambda = 0.71069 A, mu = 0.07 mm-1, F(000) = 1036, T = 293 K, final R = 0.064 for 2738 independent reflexions. Two independent molecules constitute the asymmetric unit, together with a toluene molecule. Parallel investigations of the title compounds by single-crystal X-ray analysis and theoretical calculations have converged in showing an extended configuration of the side chain attached at the C8 atom of the ergoline nucleus.

Synthesis and structure determination of products from addition of dimethyl acetylenedicarboxylate to 2,3-dihydro-2-thioxoquinazolin-4(1H)-one. X-Ray molecular structure of the dimethyl esters of 1,2-dihydro-5-oxo-5H-thiazolo[3,2-a]quinazoline-1,2-dicarboxylic, 2,3-dihydro-5-oxo-5H-thiazolo[2,3-b]quinazoline-2,3-dicarboxylic, and 5-oxo-5H-thiazolo[2,3-b]quinazoline-2,3-dicarboxylic acids

The addition of dimethyl acetylenedicarboxylate to 2,3-dihydro-2-thioxoquinazolin-4(1H)-one afforded four main cycloadducts, the structures of which were unequivocally solved by 13C n.m.r. spectroscopy and confirmed by X-ray crystallographic analysis. The products were identified as dimethyl 1,2-dihydro-5-oxo-5H-thiazolo[3,2-a]quinazoline-1,2-dicarboxylate, dimethyl 2,3-dihydro-5-oxo-5H-thiazolo[2,3-b]quinazoline-2,3-dicarboxylate, dimethyl 5-oxo-5H-thiazolo[2,3-b]quinazoline-2,3-dicarboxylate, and tetramethyl 2,2′-(1″,2″,3″,4″-tetrahydro-4-oxo-2-thioxoquinazoline-1″,3″-diyl)difumarate.

X-Ray and nuclear magnetic resonance structural study of acylglyoximes and related substances

A series of reactions used in the literature to synthesize acylglyoximes were reinvestigated and the mixtures of products obtained resolved by chromatography. NMR spectroscopy revealed that some of the derivatives described in literature as dioximes actually have an isoxazoline structure. X-Ray analysis was employed to establish unequivocally the structures of syn-diacetylglyoxime and the (Z)-3-acetyl-5-hydroxy-4-hydroxyimino-5-methyl-4,5-dihydroisoxazole hemihydrate. In addition, the structure of the derivative produced by treatment of 5-hydroxy-4-hydroxyimino-3-methyl-5-phenyl-4,5-dihydroisoxazole with dinitrogen tetraoxide in dry diethyl ether is also described.