A new and convenient route to optically active 2-phosphoryl-3-oxo-5-alkyl/-aryltetrahydrofurans and their reactions

The two enantiomers of 4-hydroxy-2-oxo-4-alkyl/-arylalkyl-phosphonates were prepared chemoenzymatically and converted to chiral 2-phosphoryl-3-oxo-5-alkyl/-aryl tetrahydrofurans using an intramolecular O-H insertion reaction catalyzed by rhodium(II) acetate. The potential biological activity of the resulting tetrahydrofurans is of much interest. The presence of the beta-ketophosphonate skeleton in these heterocycles allowed their use as substrate in the cyclic Horner-Wadsworth-Emmons reaction with aldehydes or ketones furnishing chiral alpha,beta-unsaturated ketones - a new class of building block in organic synthesis. ((C) Wiley VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004).