Mild, Racemization Free Cleavage of Ketone SAMP-Hydrazones with Oxalic Acid - Recycling of the Chiral Auxiliary

Dieter Enders; Thomas Hundertmark; Ryszard Lazny

doi:10.1055/s-1998-1765

Synlett 1998; 1998(7): 721-722
DOI: 10.1055/s-1998-1765

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Mild, Racemization Free Cleavage of Ketone SAMP-Hydrazones with Oxalic Acid - Recycling of the Chiral Auxiliary

Dieter Enders^* , Thomas Hundertmark, Ryszard Lazny

^*Institut für Organische Chemie, Rheinisch-Westfälische Technische Hochschule, Professor-Pirlet-Straße 1, D-52074 Aachen, Germany; Fax [int] +2 41/88 88-1 27; E-mail: Enders@RWTH-Aachen.de

Abstract

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Cleavage of ketone SAMP-hydrazones 1a-f with a saturated aqueous oxalic acid solution gives the corresponding ketones 2a-f in excellent yields and with high enantiomeric purity (ee = 90-99%). The chiral auxiliary SAMP is recovered from the aqueous phase in good yield (85%) and with unchanged enantiomeric purity. This racemisation free cleavage procedure is compatible with functionalities sensitive to oxidative cleavage conditions, such as ozonolysis, or to strong acids.

hydrazone cleavage - SAMP hydrazones - oxalic acid - auxiliary recycling - optically active ketones

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