1,3-Thioxanes reduction

Thioxanes (60) give similar ring-opening reactions but the subsequent reaction to lose oxygen is not observed.1,3-Dithiolanes such as the cis and trans forms of (61) can be isomerized by Lewis acids but fail to undergo reduction with H2AICI this may be a consequence of solubility problems. 

For the oxazaboroHdine-catalyzed reduction of prochiral ketones various borane reductants are employed. Borane-tetrahydrofuran and borane-dimethyl sulfide are the most frequently used reductants. Borane-l,4-thioxane [34], dibo-rane, catecholborane [35, 36, 37, 38], and diethylanihne-borane [39] are also useful borane reductants in this reduction system. 

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