Carboxylic acids reaction with vinyl boranes

Triple bonds can be monohydroborated to give vinylic boranes, which can be reduced with carboxylic acids to cis alkenes or oxidized and hydrolyzed to aldehydes or ketones. Terminal alkynes give aldehydes by this method, in contrast to the mercuric or acid-catalyzed addition of water discussed at 15-4. However, terminal alkynes give vinylic boranes (and hence aldehydes) only when treated with a hindered borane such as 47, 48, or catecholborane (p. 798)," or with BHBr2—SMe2. The reaction between terminal alkynes and BH3 produces 1,1-... 

Other reports deal with a pyrrolidine-catalysed homo-aldol condensation of aliphatic aldehydes (further accelerated by benzoic acid), a diastereoselective aldol-type addition of chiral boron azaenolates to ketones,the use of TMS chloride as a catalyst for TiCU-mediated aldol and Claisen condensations, a boron-mediated double aldol reaction of carboxylic esters, gas-phase condensation of acetone and formaldehyde to give methyl vinyl ketone, and ab initio calculations on the borane-catalysed reaction between formaldehyde and silyl ketene acetal [H2C=C(OH)OSiH3]. ... 

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