(1R,2R,3S,5R), [168286-10-0]; (1S,2S,3R,5S), [69363-09-3] · C10H19NO · (MW 169.26)
(reagent used as a chiral source in stereoselective reactions)
Alternate Name: ATBH, 3-amino-2-hydroxypinane
Physical Data: (1R,2R,3S,5R) mp 48-49.5 °C, [a]D22 +13.1 (c 1.0, CHCl3);1 (1S,2S,3R,5S) mp 45-46.5 °C, [a]D22 -14.3 (c 1.0, CHCl3).1
Solubility: soluble in most organic solvents; e.g. THF, CH2Cl2, CHCl3, EtOAc.
Form Supplied in: colorless crystals; not commercially available.
Analysis of Reagent Purity: 1H NMR, IR, elemental analysis.
Preparative Methods: optically pure (1R,2R,3S,5R)-3-amino-2,6,6-trimethylbicyclo[3.1.1]heptan-2-ol (ATBH) can be prepared from optically impure (1R,5S)-a-pinene (
Purification: recrystallization from ethyl acetate-hexane.
Handling, Storage, and Precautions: hygroscopic crystals. Use in a fume hood.
The reaction of ATBH with trimethylboroxine by refluxing in toluene affords the chiral B-methyl oxazaborolidine in high yield (
Reaction of ATBH with trimethyl borate in THF presumably affords the B-methoxy oxazaborolidine, which effectively catalyzes asymmetric borane reduction of prochiral ketones. Thus the borane reduction of acetophenone with the reagent prepared in situ from 0.1 equiv of ATBH and 0.12 equiv of trimethyl borate provides (S)-2-phenethyl alcohol in 93% yield with 95.5% ee (
The in situ generated catalyst from ATBH and trimethyl borate has also been used in the stereoselective reduction of a-oxoketoxime ethers to prepare the corresponding chiral 1,2-amino alcohols.4 Thus the asymmetric borane reduction of buta-2,3-dione monoxime ether followed by acidic work-up and subsequent reaction with benzyloxycarbonyl chloride affords a 90% yield of N-(Z)-3-aminobutan-2-ol with excellent enantioselectivities (
The modified procedure for asymmetric borane reduction is applicable to the stereoselective synthesis of N-benzoylsphinganine.5 Reduction of a-oxoketoxime trityl ethers 1 and 2 using catalyst prepared in situ from (1R,2R,3S,5R)-ATBH and trimethyl borate proceeds in high yields with high enantioselectivities (
Chiral tricyclic lactams can be prepared from (1R,2R,3S,5R)-ATBH and g-keto acids by heating in toluene with a catalytic amount of p-toluenesulfonic acid (
Aburahi Laboratories, Shionogi & Co., Ltd., Japan