Diphenylphosphinoyl aryl imines

The Hatakeyama group later reported the use of catalyst 103 for the asymmetric aza-MBH reactions of HFIPA with activated aromatic imines [96]. The aza-MBH reactions of four different diphenylphosphinoyl aryl imines (109) with HFIPA were promoted using 10 mol% 103 and afforded the corresponding a-methylene-/ -amino acid derivatives (110) in reasonable yields (42-97%) and moderate -values (54-73% Scheme 6.13). Aliphatic imines were not suitable substrates for the reaction due to imine lability. (For experimental details see Chapter 14.10.3). 

At almost the same time, Hatakeyama et al. investigated the (3-ICD catalyzed aza-MBH reaction of various aryl diphenylphosphinoyl imines 146 and 1,1,1,3,3,3-hexafluoroisopropyl acrylate (HFIPA), affording the (S)-product 147, in up to 97% yields with high ees, in DMF at low temperature (Scheme 2.70). Notably, the absolute stereochemistry of the aza-MBH adducts is opposite to that of adducts obtained from the analogous MBH reaction. With (3-ICD as catalyst, imines give rise to (5)-enriched adducts, in contrast to aldehydes, which afford (i )-products. A plausible mechanism was proposed. Moreover, the utility... 

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