Aldehydes with deuterated alpine-borane

Reduction of aldehydes labeled with deuterium or tritium leads to primary alcohols which are chiral by virtue of the label. Alternatively, the label can be introduced by the use of deuterated Alpine-Borane, which can be prepared by hydroboration with 9-borabicyclo[3.3.1]nonane-... 

Therefore, this avoids the necessity of prior preparation [6] of 1-deuterated aldehydes. The absolute configuration of the major products are consistently K)- when deuterated Alpine-Borane (from (+)-a-pinene) is used for the reduction. The product of (S)-configuration is readily obtained by using deuterated B-3-pinanyl-9-BBN prepared from (-)-a-pinene and 9-BBN-9-D. On the other hand, reduction of deuterated aldehyde with Alpine-Borane from (-h)-a-pinene affords (S)-alcohols and (f )-alcohols are obtained when (-)-a-pinene is used (Chart 26.3). 

Enantioselective reduction is not possible for aldehydes, since the products are primary alcohols in which the reduced carbon is not chiral, but deuterated aldehydes RCDO give a chiral product, and these have been reduced enantioselectively with B-(3-pinanyl)-9-borabicyclo[3.3.1]nonane (Alpine-Borane) with almost complete optical purity. ... 

---