Dicyclopentylboryl triflate

Diastereoselective addition of a propionate unit to an achiral aldehyde is an important process in organic synthesis (see Section 1.7.2.3 for the reaction with chiral aldehydes). This process can be achieved with full control by the judicious choice of a thiol ester and a dialkylboryl triflate. As shown in Scheme 16, the (0)-enolate (19) generated from S-r-butyl propanethioate, dicyclopentylboryl triflate and diisopropylethylamine furnishes, upon reaction with an aldehyde, the anti aldol product (20). The syn product (21) is obtained from the Z(0)-enolate (22) derived from the reaction of 5-phenyl propanethioate with 9-borabicyclo[3.3.1]non-9-yl triflate (9-BBNOTf). 

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See also in sourсe #XX -- [ ]

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