摘要：

The ready synthesis and ease of dialkylboron chlorides, R2BCI, compared to triflates, R2BOTf, give the chlorides a significant advantage as reagents to achieve the conversion of ketones into enol borinates, regiospecifically and quantitatively. This made possible the first study of the effect of changes in the leaving group on the ratios of E-:Z-enol borinates produced. Indeed, a systematic study of the effect of the steric requirement of the R group (R=9BBN vsChx2), the amine (Et3N vs i-Pr2EtN), and the leaving group (CL vs OTf), with two representative ketones, propiophenone and diethyl ketone, revealed a controlled shift from preferential formation of the Z-enol borinates to the E-enol borinates. The technique was applied to other representative ketones and selective conversion to both E-enol borinates (approx. 99%) and Z- enol borinates (approx. 80-99%) and Z-enol borinates (97-99%) has been achieved. Enol borinates are valuable intermediates in organic synthesis.

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