AROMATIC ALDONITRONES OF 2-(HYDROXYAMINO)BENZYL ALCOHOL AND THEIR CYCLIC ISOMERS - CRYSTAL AND MOLECULAR-STRUCTURES OF A 1-HYDROXY-1,2-DIHYDRO-4H-3,1-BENZOXAZINE, A BORON CHELATE, AND ITS PARENT NITRONE LIGAND

The synthesis of a series of C-aryl-N-[2-(hydroxymethyl)phenyl]nitron 5 (that can also exist under certain conditions as isomeric 1-hydroxy- 2-aryl-1,2-dihydro-4H-3,1-benzoxazines 8), via 2-(hydroxyamino)benzyl alcohol, 4, and their subsequent reactions with oxybis(diphenylborane) , (Ph2B)(2)O, leading to the 5-(arylmethylene)-7,7-diphenyl-6,8-dioxa a-7-borata-5H-6,7,8,9-tetrahydrobenzocycloheptenes 6 are described. Cr ystals of -(4-methoxyphenyl)-1,2-dihydro-4H-3,1-benzoxazine, 8b, are m onoclinic, a = 9.379(2), b = 10.699(2), c = 12.9392(7) Angstrom, beta = 99.916(2)degrees Z= 4 (two independent molecules), space group Pa; t hose of C- ylamino)phenyl]-N-[(2-hydroxymethyl)phenyl]nitrone 5c, are monoclinic, a = 7.687(1), b = 7.891(1), c = 11.5053(9) Angstrom, beta = 92.781(9)degrees Z= 2, space group P2(1); and those of ia-7-borata-5 H-6,7,8,9-tetrahydro-benzocyloheptene 6a, are monoclinic, a = 10.771(1 ), b = 13.1057(9), c = 16.8724(7) Angstrom, beta = 90.005(5)degrees Z = 4, space group P2(1)/n. The structures were solved by direct methods and refined by full-matrix least-squares procedures to R(F-2) = 0.120 (R-w(F-2) = 0.135) for all 3149 reflections (R(F) = 0.071, R-w(F) = 0 .063 for 1500 reflections with I greater than or equal to 3 sigma(I)) for 8b and R(F) = 0.035 and 0.036 (R-w(F) = 0.031 and 0.038) for 1071 and 3594 reflections with I greater than or equal to 3 sigma(I), respe ctively, for 5c and 6a. Compound 8b is the first structurally characte rized 1-hydroxy-1,2-dihydro-4H-3,1-benzoxazine derivative and 6a featu res a relatively rare seven-membered boron-containing heterocycle.