Carbonyl reduction under Meerwein-Ponndorf-Verley conditions

Carbonyl reduction under Meerwein—Ponndorf—Verley conditions 

The Meerwein-Ponndorf-Verley reaction is a useful method for the reduction of carbonyl groups to alcohols. Most typically, aluminium isopropoxide is used as a reducing agent. The acetone produced can be easily removed by distillation, thus driving the equilibrium reaction in the desired direction. When the carbonyl compound was refluxed 

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Carbonyl reduction under Meerwein—Ponndorf—Verley conditions... 

In steroids, the carbonyl group at C-3 is generally the most reactive and that on C-ll the least reactive enabling chemoselective reductions of polyoxosteroids5. The following example demonstrates this chemoselectivity, as well as excess formation of the thermodynamically more stable alcohol by the Meerwein-Ponndorf-Verley reduction of a 7,11-diketone 21l82. The acetic ester is cleaved under these conditions. 

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