Lithium Alkylborohydrides

Synthesis of pure enantiomers. Brown and Singaram1 have reviewed the chiral organoboranes obtained from (+)- and (- )-pinene and their use for synthesis of optically pure amines, halides, hydrocarbons, lithium alkylborohydrides, ketones, aldehydes, a-chiral acids, esters, nitriles, alkynes, and alkenes. 

That means that this method is a neat little way one can get the ever lovely MDEA (Methylenedioxyethyl amphetamine, the softer cousin of X). Strike hears you asking So if one uses lithium tri-methylborohydride can one get methamphetamine out of that nitro group . Good question. Unfortunately the answer is no. The authors say Interestingly, N-alkylated products were not produced when other alkylborohydrides were used." Fair enough. Here s the recipe ... 

Alkylborohydrides are also used as reducing agents. These compounds have greater steric demands than the borohydride ion and therefore are more stereoselective in situations in which steric factors come into play.72 These compounds are prepared by reaction of trialkylboranes with lithium, sodium, or potassium hydride.73 Several of the compounds are available commercially under the trade name Selectrides .74... 

The atmospheric pressure carbonylation of undissociated alkali-metal tri-alkylborohydrides is unsuccessful, but rapid reaction has been found to occur if catalytic amounts of free trialkylborane are present (as is the case for lithium trialkylborohydrides), or are added to the mixture (Scheme 4). Hydrolysis of the... 

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