Enantiospecific synthesis of 4-(4′-methoxyphenyl)-hexan-3-one as precursor for optically active (p S) or (p R) isomer of ( Z) or ( E)-3-(2′-(( N, N-dimethylamino)methylferrocenyl)-4-(4″-methoxyphenyl)-hex-3-ene

• Published in: Tetrahedron: asymmetry 1998-01, Vol.9 (2), p.259-269
• Main Authors: Malézieux, Bernard, Gruselle, Michel, Troitskaya, Ludmila, Sokolov, Viatcheslav
• Format: Article
• Language: English
• ISSN: 0957-4166; 1362-511X
• DOI: 10.1016/S0957-4166(97)00636-8

We describe herein an original method for the preparation of enantiomerically pure ( Z)- or ( E)-3-(2′-(( N, N-dimethylamino)methylferrocenyl)-4-(4″-methoxyphenyl)-hex-3-ene possessing a p( S) or p( R) plane of chirality. The key step of the synthesis lies in obtaining enantiomerically pure ( R) or ( S) 4-(4′-methoxyphenyl)-hexan-3-one whose reaction with the lithiated N, N-dimethylaminomethylferrocene leads to two enantiomerically pure amino-alcohol diastereomers (p S,3 S,4 R) and (p R,3 S,4 R), or (p S,3 R,4 S) and (p R,3 R,4 S) respectively. Subsequent dehydration yields a mixture of three olefins, namely, two trisubstituted olefins and either the ( Z)- or ( E)-tetrasubstituted olefin with respect to the starting amino-alcohol diastereomer. Additionally we obtained the enantiomerically pure ( R)- and ( S)-4-phenyl-hexan-3-one and the corresponding diastereomeric amino-alcohols.