Why I love BMS

I am not referring to Bristol-Myers Squibb as I have no reason to have any feeling towards that organization. Today it is all about borane-dimethylsufide (BMS), which is a well-known borane reagent in synthetic organic chemistry. The complex has a lot going for it, such as good solubility in organic solvents and increased thermal stability compared to other borane reagents.

Over the years, I have marvelled at the versatility of BMS. Today I have read a great paper by the Kanai team from Japan. This JACS report suggests a new use to the time-honored reagent. Below you see what happens to a fairly elaborate acid-terminated substrate. The authors were able to demonstrate that engagement of the acid by a catalytic amount of BMS results in the formation of a boron enolate, which later enables Mannich-type chemistry. DBU plays the role of a stoichiometric base here. There are not many ways to run similar chemistry using acid precursors, which is why this report is a pleasant surprise, especially given the simplicity of the reaction conditions. The paper also reminds us of Zakarian’s alkylation chemistry (http://pubs.acs.org/doi/abs/10.1021/ja205107x), which is another example of how one can effect direct transformations of enolizable carboxylic acids under fairly mild conditions while using inexpensive reagents.

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http://pubs.acs.org/doi/abs/10.1021/jacs.5b04175

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