Diastereoselective Synthesis of<i>syn</i>-Alkanetriols from a Glyceral Derivative via<scp>k</scp>-Selectride Reduction: Application to the Synthesis of a Pheromone of the Sugarcane Weevils
k-selectride reduction of commercially available d-mannitol derived ketones 2b-i produced the corresponding alcohols 3b-i in good yields and with absolute syn-selectivity in almost all the cases. It was proposed that the bulky cyclohexylidene moiety of 3 has a significant role in favoring the reduction with k-selectride via Felkin-Anh model. Subsequently, one of the reduction product 3c has been exploited to synthesize the pheromone I of sugarcane weevil.
reagent (R 2 MgX) or the ketone also reduced the diastereoselectivity of the reaction. When, with regard to chain lengths of the alkyl groups in the Grignard reactions, R 2 > R 1 , the reaction proceeded with SYN selectivity, and vice versa. In general, the C-3 epimers of the target tertiary carbinols could be prepared easily by altering the sequence of the addition of the Grignard reagents (R 1 MgX and