| abstract |
1-Oxo-2,4-dihydroxy- (or 2-hydroxy-4-halo)-butane derivatives of formula (I) and pentene-3,5-diol derivatives of formula (X) are new. R1 = H, 1-20C alkyl, aryl or 7-20C aralkyl; R2 = H or protecting group; R3 = OH, halo or OR6; R6 = protecting group; R4 = H or 1-10C alkyl; R5 = H, 1-10C alkyl, aryl or 7-20C aralkyl; provided that in (I) (i) R2 is other than benzyl or tert. butyldimethylsilyl (TBDMS) if R3 = -O-TBDMS; and (ii) R2 and R6 do not together form -CH-(p-methoxyphenyl). A multi-stage process for preparing compounds (I; R1 other than H), in which the above provisos do not apply, optionally with further conversion of the product to a Wittig salt via (X), is claimed. |