Asymmetric Michael Additions via 2,2-Dimethyl-1,3-dioxan-5-one SAMP-Hydrazone. Distereo- and Enantioselective Synthesis of Protected 3-Substituted 4,6-Dihydroxy-5-oxo Esters

Dieter Enders; Dagmar Kownatka; Thomas Hundertmark; Oleg F. Prokopenko; Jan Runsink

doi:10.1055/s-1997-1397

Synthesis 1997; 1997(6): 649-652
DOI: 10.1055/s-1997-1397

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Asymmetric Michael Additions via 2,2-Dimethyl-1,3-dioxan-5-one SAMP-Hydrazone. Distereo- and Enantioselective Synthesis of Protected 3-Substituted 4,6-Dihydroxy-5-oxo Esters

Dieter Enders^* , Dagmar Kownatka, Thomas Hundertmark, Oleg F. Prokopenko, Jan Runsink

^*Institut für Organische Chemie, Rheinisch-Westfälische Technische Hochschule, Professor Pirlet-Straße 1, D-52074 Aachen, Germany, Fax +49(241)8888127; E-mail: Enders@RWTH-Aachen.de

Abstract

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The metalated 2,2-dimethyl-1,3-dioxan-5-one SAMP-hydrazone (S)-3 adds to enoate Michael acceptors 2 with high asymmetric induction. Oxidative cleavage of the SAMP auxiliary furnishes selectively protected 3-substituted 4,6-dihydroxy-5-oxo-esters (3S/R,4S)-5 in good yields (40-79%, two steps) with high diastereo- and enantiomeric excesses (de = 91-96%, ee = 89-97%). The relative configuration was determined by NMR spectroscopy and the absolute configuration by analogy with earlier results.

asymmetric synthesis - Michael addition - SAMP-hydrazone - 2,2-dimethyl-1,3-dioxan-5-one - 4,6-dihydroxy-5-oxo esters

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