Allyl- and Crotylborane Reagents

Reagents 195, 220, 212 and 229 are synthesized starting from commercially available yff-methoxydiisopinocampheylborane, (-)-Ipc2BOMe or (4-)-lpc2BOMe. 

RCHO reagent major product temp, solvent % yield %ee 

BFyOEt2 wa.s used as an additive in this reaction. ) Yield not reported. 

The ( lpc)2BAll reagent 195 is prepared from the reaction of (-f-IpczBOMe with allylmagnesium bromide followed by removal of the salts by filtration 

Brown and co-workers have demonstrated that these reagents react in a highly diastereo- and enantioselective manner with achiral aldehydes (Table 11-13) [112, 113, 140, 142, 165]. 

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From the range of synthetic applications of Brown s pinene-derived allyl- and crotylborane reagents illustrated in these selected examples, it is clear that they are excellent reagents for the synthesis of chiral homoallylic alcohols from chiral and achiral aldehydes alike. That so many researchers have applied these reagents in their research also attests to the great utility of these reagents in organic synthesis. 

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