NMR study of spirophosphoranes derived from 2-aminophenols

Multinuclear magnetic resonance experiments were performed (H-1, C-13, P-31 and N-15) for P-H phosphoranes derived from 2-aminophenol, 4-tert-butyl-2- aminophenol, and 4,6-di-tert-butyl-2-aminophenol. Selective heteronuclear H -1{N-15} double resonance experiments and two-dimensional N-15/H-1 HETCOR e xperiments enabled us to determine various signs of coupling constants (e.g ., (2)J(P-31, N-1, H-1) > 0; (1)J(P-31, N-15) < 0). The H-1-coupled N-15 NM R spectrum recorded by the INEPT pulse sequence shows the splitting due to (1)J(P-31, N-15) and (2)J(N-15, P, H-1). The latter value is useful for pol arization transfer experiments from H-1 to N-15, once the hydrogen atoms of the N-H functions ave replaced by other groups. Isotope-induced chemical s hifts 1 Delta(14/15)N(P-31) were measured by using the INEPT-HEED pulse seq uence. (C) 2000 John Wiley & Sons, Inc.