Vinylboron dichloride

The syntheses of 2-carboxy-, 2-amino-, and 2-hydroxy-derivatives of 1,7-dicarba-c/ojo-dodecaboranes have been reported. All were produced in good yields by simple routes from2-vinyl-l, 7-dicarba-c/ojo-dodecaborane(12), which was itself prepared by the reaction of vinylboron dichloride with the dilithium salt of undecahy ido-7,9-dicarba- /db-undecaborate(2—). 

Monoalkylthallium compounds are usually prepared either by the reaction of dialkylthallium carboxylates and mercury(II) carboxylates (equation 22), or by reacting dialkylthallium halides with Br2 or I2 (equation 23). Aryl- and vinylthallium dichlorides are prepared conveniently by the reaction of aryl- and vinylboronic acid, respectively, with excess TICI3 in aqueous solution (equation 24). > ... 

Vinylboronic acids undergo analogous reactions to give the mono- and divinyl-thallium derivatives in high yields " with retention of configuration, e.g., heating a 1 1 cis-propenylboronic acid and Tl(III) chloride in aq ether for 8.5 h produces 30% cis-propenylthallium dichloride and 30% bis(cis-propenyl)thallium chloride. The same reaction with trans-propenylboronic acid produces 28% trans-propenylthallium dichloride and 67 % bis(trans-propenyl)thallium chloride. 

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