A Straightforward Synthesis of (3S)-4-Methoxybutane-1,3-diol and its Use as Chiral Auxiliary for the Preparation of (pS)-1-(Diphenylphosphino)-2-formyl-1′,2′,3′,4′,5′-pentamethylferrocene

ABSTRACT (3S)-4-Methoxybutane-1,3-diol [(S)-4], an important auxiliary for the synthesis of planar-chiral metallocenes, has been obtained from (S)-1,2,4-butanetriol via formation of an isomerically pure acetal of P-nitrobenzaldehyde, O-methylation and hydrolysis. Diol (S)-4 was used in a synthesis of the new planar-chiral ferrocene (pS)-1-(diphenylphosphino)-2-formyl-1′,2′,3′,4′,5′-pentamethylferrocene [(pS)-9].