Towards the diastereoselective functionalization of non-racemic acetal derivatives of eta(6)-arylcarbonyl complexes of tricarbonylchromium

(S)-Butane-1,2,4-triol (2) has been investigated as a potential chiral auxi liary for the formation of non-racemic acetals derived from eta(6)-arylcarb onyl complexes of tricarbonylchromium. Predominantly the cis dioxan (5) was formed from benzaldehyde, leading to preparation of the eta(6)-Cr(CO)(3) c omplex (16), and of the derived complexes (23) and (24). Lithiation-electro phile quenching of these complexes gave a mixture of products arising from ortho and benzylic functionalization. Reaction of acetophenone, or of the e ta(6)-Cr(CO)(3) complexes (45) or (46), with either the triol (2) or its tr is(silyl) ether (15) under conditions of kinetic or thermodynamic control g ave an inseparable mixture of acetals.