Diastereoselective reduction of carbonyls

The development of reliable methods for the diastereoselective reduction of carbonyl compounds in a wide range of acyclic systems has been an area of explosive growth in recent years. This was prompted by the requirements of modem total synthesis in which redundant diastereoisomers are avoid, - together with enhanced theoretical understanding of stereoselectivity which allows rationalization of the results. 

Diisobutylaluminum hydride (DIBAH) is undoubtedly one of the most common reducing agents in organic synthesis and recent interest in the synthetic utility of DIBAH has been directed toward diastereoselective reduction of carbonyl substrates. High, i-syn diastereoselectivity has been achieved in the chelation-controlled reduction of P-hydroxy ketones with DIBAH in THF [49], The choice of solvents strongly affects the selectivity. Use of CH2CI2 or toluene in place of THF did not show any diastereoselectivity. 

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