Luche-type reduction

Two mechanistic possibilities were considered in the stereoselective reduction of (Z)-/3-sulfinyl enones either by NaBH4 or diisobutylaluminium hydride (DIBAL) to enantiomerically pure (Z)-jS-sulfinyl allylic alcohols of either handedness in the presence of LaCl3, which acted as chelating agent. One possibility was essentially a Luche-type reduction model. The other invoked formation of an intermediate sterically... 

If it is assumed that the Mitsunobu glycosidation reaction described above proceeds through an SN2-type process with inversion of configuration at the anomeric position, then it follows that the desired / -glycoside can be formed selectively if pure a-lactol 17 is used in the reaction. Unfortunately, the /Mactol isomer of 17 is thermodynamically more stable than the a-diastereoisomer and is formed almost exclusively if the system is allowed to fully equilibrate. In the protic medium used for the Luche reduction, a signifi-... 

The utility of the selective reduction techniques described in these sections is so pronounced that the term Luche reduction is essentially generic. Natale s review (1983) is recommended for a more extensive examination of the types of synthetic methodology that have evolved from this base. 

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