NMR study of spirophosphoranes derived from 2‐aminophenols

Multinuclear magnetic resonance experiments were performed (¹H, ¹³C, ³¹P, and ¹⁵N) for P‐H phosphoranes derived from 2‐aminophenol, 4‐tert‐butyl‐2‐aminophenol, and 4,6‐di‐tert‐butyl‐2‐aminophenol. Selective heteronuclear ¹H{¹⁵N} double resonance experiments and two‐dimensional ¹⁵N/¹H HETCOR experiments enabled us to determine various signs of coupling constants (e.g., ²J(³¹P, N, ¹H) > 0; ¹J(³¹P, ¹⁵N) < 0). The ¹H‐coupled ¹⁵N NMR spectrum recorded by the INEPT pulse sequence shows the splitting due to ¹J(³¹P, ¹⁵N) and ²J(¹⁵N, P, ¹H). The latter value is useful for polarization transfer experiments from ¹H to ¹⁵N, once the hydrogen atoms of the N‐H functions are replaced by other groups. Isotope‐induced chemical shifts ¹Δ^14/15N(³¹P) were measured by using the INEPT‐HEED pulse sequence. © 2000 John Wiley & Sons, Inc. Heteroatom Chem 11:11–15, 2000