B-3-Pinanyl-9-borabicyclo[3.3.1]nonane

(R) [173624-47-2] C18H31B (MW 258.30) InChI = 1S/C18H31B/c1-12-16-10-13(18(16,2)3)11-17(12)19-14-6-4-7-15(19)9-5-8-14/h12-17H,4-11H2,1-3H3/t12-,13+,14-,15+,16-,17-/m1/s1 InChIKey = VCDGSBJCRYTLNU-PHPOFCCKSA-N (S) [42371-63-1] InChI = 1S/C18H31B/c1-12-16-10-13(18(16,2)3)11-17(12)19-14-6-4-7-15(19)9-5-8-14/h12-17H,4-11H2,1-3H3/t12-,13+,14-,15+,16-,17+/m1/s1 InChIKey = VCDGSBJCRYTLNU-VRXFMZDNSA-N (asymmetric reducing agent which is particularly effective for aldehydes1 and alkynic ketones2) Alternate Name: Alpine-Borane®. Solubility: sol most organic solvents. Form Supplied in: 0.5 M solution in THF. (R)-Alpine-Borane is prepared from (+)-α-pinene, and (S)-Alpine-Borane from (−)-α-pinene. High purity α-pinene is available commercially. Preparative Methods: readily prepared by hydroboration of either (+)- or (−)-α-pinene4 with 9‐Borabicyclo[3.3.1]nonane Dimer (9-BBN) (eq 1). (1) Since the neat reagent is most effective, the solvent is usually removed before reduction of the ketone. Brown has reported a synthesis using neat α-pinene and solid 9-BBN.5 The deuterium- or tritium-labeled compound may be prepared by hydroboration with labeled 9-BBN.6 Alternatively B-methoxy-9-BBN may be reduced with LiAlD4 (see Lithium Aluminum Hydride) in the presence of α-pinene.7, 8 Handling, Storage, and Precautions: organoboranes are spontaneously flammable in air and must be handled under an inert atmosphere. They are generally stable to moisture. Alpine-Borane can slowly undergo dehydroboration.3 Use in a fume hood.