Diboryl enediolates

Although simple alkyl esters (ethyl propionate) fail to enolize with the boryl triflate reagents under normal conditions, the more acidic acyloxyboranes 66 readily form the diboryl enediolates 67 (eq. [52]) (6a,66). Several interesting trends are noted in the data included in Table 23. Since previous studies have demonstrated that enolate geometry strongly correlates with product stereochemistry, enediolate 67 has been employed to directly compare the reactivities... 

It has been shown by Evans et al. that the aldol reaction of diboryl enediolates (23), with one exception, exhibit varying degrees of anti stereoselection (Scheme 18). This implies that (23) reacts more effectively as an (0)-boryl enolate than as a Z(0)-enolate. ... 

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See also in sourсe #XX -- [ ]

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