V. Nevalainen et al., A NEW CLASS OF OXAZABOROLIDINE DERIVATIVES DISCOVERED, KETONES AND ALDEHYDES AS BIDENTATE LIGANDS, Tetrahedron : asymmetry, 6(6), 1995, pp. 1431-1440
Novel adducts (5'a-f) of H2CO/Me(2)CO and H(2)BOR (R = H, Me) to amino
borane (1'a), aminohydroxy-borane (1'b) and 1,3,2-oxazaborolidine (1'c
) were studied by means of ab initio MO (RHF) methods. Energies of the
formation of the adducts were clearly exothermic [e.g. -140 and -134
kJ mol(-1) (MP2/6-31G//MP2/6-31G*) in the case of H2(C)O - H2BOH addu
ct of 1'a and 1'c]. All the Me(2)CO adducts were found to be slightly
less stable than the corresponding H2CO adducts. In all the adducts (5
'a-f) studied the carbonyl system was found to behave as a bidentate l
igand. All the bidentate adducts were found to be significantly more s
table than the related monodentate adducts (4'a-c). Activation of the
carbonyl moiety of the bidentate adducts resembles that of the related
adducts of N-sulfonylated oxazaborolidines (7).