The 6-oxo group in 2,3 : 20,22-di-O-isopropylidene derivatives of 20-hydroxyecdysone and its 24,25/25,26-anhydro analog is reduced with NaBH 4 -CeCl 3 in a stereoselective fashion to afford the corresponding 6α-alcohols. In the first case, the reaction is accompanied by dehydration to give Δ 14 -bond. Reduction of the same substrates with NaBH 4 or LiAlH 4 in the absence of CeCl 3 leads to mixtures of 6α-and 6β-hydroxy derivatives, the latter prevailing. In all cases, epimerization at C 5 occurs.
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