Alpine-hydride

Alpine-Hydride and NB-Enantride are trademarks of the Sigma-Aldrich Corporation. 

Hesse and coworkers have used this strategy for the preparation of various macrolides.173 For example, Michael addition of 2-nitrocyclodecanone methyl vinyl ketone followed by reduction with (5)-alpine-hydride gives the nitrolactone in 72% yield. Radical denitration of the nitrolactone with Bu3SnH gives (+)-(5)-tetradecan-13-olide in 44% yield (Eq... 

Optical active phoracantholide I (VII/126) was observed when ( )-2-nitro-2-(3 -oxobu-tan-4-yl)cyclohexanone was reduced with (S)- or (i )-Alpine-Hydride [85],... 

Among the chiral borohydrides, ate complexes generated from a-pinene, such as Alpine-hydride 3.64 and related reagents, reduce 2-octanone or acetylcyclohexane... 

Trialkylborohydrides prepared from optically active alkenes may be used for asymmetric-reduction. For example, reaction of fcrt-butyllithium with Alpine-borane, prepared by hy-droboration of ( + )- or ( —)-a-pinene with 9-borabicyclo[3.3.1]nonane (see Section D.2.3.5.1.), provides Alpine-hydride. 1 his reagent reduces 1-phenylethanone in 17% ee72. A more effective reagent is NB-Enantride, prepared in a similar manner by treatment of the product from hydroboration of the benzyl ether of 2-(2-hydroxyethyl)-6,6-diinethylbicyclo[3.3.1]hept-2-ene (nopol. see Section D.2.3.5.1.) with toV-butyllithium73. 

Alpine-Hydride and NB-Enanatride are trade names of the Sigma Aldrich Corporation. M. M. Midland, A. Kazubski, and R. E. Woodling, J. Org. Chem., 56, 1068 (1991). 

The lithium B-(isopinocampheyl)-9-borabicyclo[3.3.1]nonane hydride (Alpine-Hydride), a highly hindered trialkylborohydride containing an asymmetric group is obtained by treatment of Alpine-Borane with f-BuLi at -78 °C (Eq. 26.20) [1]. The ketones are reduced rapidly and quantitatively to the corresponding alcohols [1] at -78 °C... 

---