Diastereo- and enantioselective synthesis of differently N,O-protected 1,3-amino alcohols with three neighbouring stereogenic centers

An efficient diastereo- and enantioselective access to all-syn-configured, differently N,O-protected 1,3-amino alcohols via a titanium tetrachloride mediated aza-enolate aldol reaction/aldehyde hydrazone 1,2-addition protocol is described. The O-TBS and N-Cbz protected title compounds are obtained after reductive N-N bond cleavage in a four steps synthesis with moderate to good overall yields (18-58%), high diastereomeric (de = 78% to greater than or equal to96%) and enantiomeric (ee greater than or equal to96%) excesses.