Diethylboryl pivalate

Several investigations have addressed the synthesis of boryl eno-lates by carbonyl enolization. Kbster has examined in detail the thermal reaction of triethylborane with substituted ethyl ketones catalyzed by diethylboryl pivalate (58) (eq. [40]) (61). The boryl pivalate 58 is undoubtedly the active reagent in this system, and it is regenerated by the illustrated protonolysis (eq. [41]) (62). The vigorous conditions employed in this procedure probably result in the generation of the equilibrated boryl enolates. The enolate ratios obtained by way of this procedure are summarized in Table 18. 

Stereochemistry of the Enolates Generated by the Reaction of Ketones and Diethylboryl Pivalate-EtsB (eq. [40]) (61)... 

German workers independently found that 1,2- 1,3-, and some 1,4-diols can be converted into bis(diethylborinates) which, on heating to 200°, lose triethylboron to give cyclic ethylboronates. Otherwise, these boronates can be prepared directly from the diols by heating with triethylboron in the presence of diethylboryl pivalate, or by dismuta-tion from equimolar proportions of diols and their bis(diethylbori-... 

The most common route to boron enolates uses the method of carbonyl enolization. Koster and coworkers employed triethylborane with diethylboryl pivalate as a catalyst under vigorous conditions, which probably led to the thermodynamic enolates (equation 31). ... 

Diethylboryl pivalate Cleavage of boron-carbon bonds catalyzed by pivalic acid derivs. Enoxyboranes from ketones... 

Diethylboryl pivalate Self-condensation of aryl ketones... 

A suspension of sarcosine and triethylborane in acetonitrile refluxed 0.5 hr. in the presence of diethylboryl pivalate -> diethylboryl sarcosinate. Y 91%. F. e., also without boryl pivalate, s. R. Koster and E. Rothgery, A. 1974, 112. ... 

The colorless, vacuum-distillable liquid [(2,2-dimethylpropanoyl)oxy]diethyl-borane (2,2-dimethylpropanoyl = pivaloyl) is a catalyst for the introduction of diethylboryl groups onto the oxygen atoms of hydroxy compounds using tri-ethylborane, Diethylborylations of hydroxy compounds have both preparative " and analytical (determination of the ethane value EZ ) uses. [(2,2-Dimethylpropanoyl)oxy]diethyIborane is itself a reagent for preparing aldol-condensation products" and for determining analytical pivalate values (PZ) of H-acidic compounds. ... 

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