2- phenyl-l,3,2-dioxaborolane

Acetonolysis of 2-phenyl-l,3,2-dioxaborolanes of D-glucitol and D-mannitol gave the 1,2-0-isopropylidene-alditols as shown for D-glucitol in Scheme 1. A similar reaction with a-D-glucofuranose 1,2 3,5-bis(benzeneboronate) gave 1,2-(9-isopropy lidene-0 -D-glucofuranose. 

Roy and Brown examined the rates and equilibrium compositions resulting from the reaction of the cyclic, unhindered phenylboronic ester 2-phenyl-l,3,2-dioxaborolane (A), with several 1,2- and 1,3- diols of various structural types (Scheme 3.1). The equilibrations are rapid (<0.1 h) in CDCI3 at 25 °C. From the equilibrium ratios in Scheme 3.1 it is obvious that six-membered dioxaborinanes are more stable thermodynamically than five-membered dioxaborolanes, and also that introduction of methyl substituents at the a position from oxygen stabilizes the cyclic esters. The very fast and complete displacement by diethanolamine is also worth noticing. Unfortunately, hexyleneglycol was not introduced in this study. 

Scheme 3.1 Ttansesteriflcation of 2-phenyl-l,3,2-dioxaborolane with diols. (Adapted with permission from ref. 23 2006 Elsevier B.V.)...

Dimethyl(phenyl)(4-(4,4,5,5-tetramethyl-l,3,2-dioxaborolan-2-yl)but-2-en-2-yl)silane (4b) Colorless oil yield 91%... 

The acid-base properties of l-methyl-l,4-dihydroborabenzene have been studied by ion cyclotron resonance. The mass spectra of several pyrazaboles as well as a series of 2-p-substituted phenyl-1,3,2-dioxaborolanes have been reported. Additionally, cyclic boronates have been utilized in the charactmzation of bifunctional compounds by mass spectrometry. ... 

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