REACTION OF 6-(CF3)- AND 6-(CH3)-2-(TERT-BUTYL)-1,3-DIOXAN-4-ONE LI ENOLATE WITH 2 EQUIVALENTS OF AN ALDEHYDE - UNUSUAL REORGANIZATIONS OF ALDOLATES

The Li enolate of -2-(tert-butyl)-6-trifluoromethyl-1,3-dioxan-4-one ( 1) reacts with isobutyraldehyde, pivalaldehyde and cyclohexanecarboxal dehyde to give unexpected aldols [3a-5a, ,2'-trifluoro-1'-hydroxyethyl )-1,3-dioxan-4-ones]. The Li enolate of (2R,6R)-2-(tert-butyl)-6-methy l-1,3-dioxan-4-one (2) reacts with pivalaldehyde to give -(tert-butyl) -5-(1'-hydroxyethyl)-1,3-dioxan-4-one (7), another ''strange'' aldol-t ype product resulting from one enolate and two aldehyde molecules. The re is an unusual reorganization involving a transacetalization process under basic conditions. The structures of two products (4a and 7) wer e determined by X-ray crystallography, and a mechanism of formation pr oposed.