Racemic t-butylphenylphosphine oxide was resolved via formation of diastereoisomeric complexes with (+)-(R)-1,1'-binaphthalene-2,2'-diol and (+)-(S)-mandelic acid. With the latter complexing agent, separation of the essentially enantiopure (-)-(S)-enantiomer was achieved in a single complexation process. Addition of paraformaldehyde to this enantiomer gave alpha-hydroxymethyl-t-butylphenylphosphine oxide with high stereoselectivity and retention of configuration at phosphorus while its reaction with methyl bromoacetate in methanol/sodium methoxide resulted in the formation of methyl t-butylphenylphosphinate with inversion at phosphorus. (C) 1999 Elsevier Science Ltd. All rights reserved.