201. Reactions of Chiral 2-(tert-Butyl)-2H,4H-1,3-dioxin-4-ones Bearing Functional Groups in the 6-Position and Diastereoselective Catalytic Hydrogenation to cis-2,6-Disubstituted 1,3-Dioxan-4-ones

Article abstract of DOI:10.1002/hlca.19870700819

(R)-5-Bromo-6-(bromomethyl)-2-(tert-butyl)-2H,4H-1,3-dioxin-4-one (2) derived from (R)-3-hydroxybutanoic acid used for substitutions and chain elongations at the side-chain C-atom in the 6-position of the heterocycle (->3-6, 10-13).Subsequent simultaneous reductive debromination and double-bond hydrogenation (Pd/C, H2) occurs with essentially complete diastereoselectivity (>98percent ds), with H transfer from the face opposite to the t-Bu group (->15-20, Table 1).Hydrolytic cleavages of the dioxanones then lead to enantiomerically pure β-hydroxy-acid derivatives (overall self-reproduction of the stereogenic center of 3-hydroxybutanoic acid or alkylation in the 4-position of this acid with preservation of configuration).