Aminophosphanes derived from chiral β-aminoalcohols and carbonyliron complexes thereof

Abstract

Phosphinites 2 and 4 derived from (−)- N-methylephedrine ( 1) and (+)- N-methyl-Ψ-ephedrine ( 3), respectively are described. The synthesis of the chiral potassium hydridoferrate complex 8 from ‘ N-methyl-diphenylephos’ ( 2) and KHFe(CO) 4 was less selective than that of the previously described chiral zwitterionic hydride 7 from ‘ N, N-dimethyl-diphenylephosium’ ( 6) and KHFe(CO) 4. Phosphines corresponding to deoxy derivatives of ‘ephos’ 2 and ‘ephosium’ 6 were envisaged. A stereoselective conversion of 2 to the hydrohexafluorophosphate of the N-methyl-diphenyldeoxyephos oxide isomer ( 5) is reported, and an approach to the ‘ N, N-dimethyl-diphenyldeoxyephosium’ ( A) has been explored by stereoselective chlorination of the quaternary N, N-dimethylephedrium ( 11). Likewise, ‘ N, N, N-trimethyl-diphenyldeoxyvalphosium’ ( B) was envisaged by chlorination of (+)- N, N, N-trimethylvalinolium ( 14). In the presence of Ph 2PLi, however, the chlorides 12a and 16 underwent elimination reactions instead of Cl − substitution, and the phosphines A and B did not form. In a reverse complexation–quaternization strategy, the ‘ N, N-dimethyl-diphenyldeoxyvalphos’–Fe(CO) 4 complex ( 20) has been selectively prepared, and subsequently converted to the corresponding ammonium complexes 21 and 20·HOTf.