Zur Umsetzung von 8a-Methoxy-3,4-dihydro-2H-1,4-benzoxazin-6(8aH)-onen mit Diazoalkanen, 2. Mitt.
作者:Manfred Schubert-Zsilavecz、Ferdinand Belaj、Robert Ott
DOI:10.1007/bf00811545
日期:1992.10
8a-Methoxy-3,4-dihydro-2H-1,4-benzoxazin-6(8aH)-ones 2 undergo regio- and stereospecific 1,3-dipolar cycloaddition reactions with diazomethane or diazoethane to yield 3,4,6 a,9,9 a,9 b-hexahydro-pyrazolo[3,4-h][1,4]benzoxazin-6(2H)-ones 3, which slowly isomerize in solution to give the 3,4,8,9,9a,9b-hexahydro-pyrazolo[3,4-h][1,4]benzoxazin-6(2H)-ones 5. The carbon of the diazoalkane dipole is attached to carbon C-8 of the benzoxazinone. The structures of the obtained products were determined by H-1- and C-13-NMR spectroscopy. An X-ray crystal structure analysis of 3a was carried out at room temperature: C11H15N3O3, M(r) = 237.26, orthorhombic, Pc2(1)n, a = 9.173 (5), b = 9.133 (4), c = 13.281 (6), V = 1112.6 (9) angstrom3, Z = 4, d(x) = 1.416 g/cm-3, mu = 0.93 cm-1, R = 4.33%, R(w) = 3.95% (919 observations, 168 parameters).