Amino-3-methyl-1,1-diphenyl-1-butanol

Dieter Enders Martin Klatt RWTH Aachen, Germany 

Solubility very sol THE, CH2CI2, MeOH not very sol water. 

Preparative Methods from valine methyl ester hydrochloride and excess Phenylmagnesium Bromide in 56% yield.  

Handling, Storage, and Precautions no special information available. In general, however, it is advisable that all reactions with this reagent be conducted in a well ventilated fume hood. Care should be exercised to avoid contact of this reagent and the derived oxazaborolidine catalyst with the eyes and skin. 

Reduction of a-chloroacetophenone using the catalyst prepared from the related (5)-diphenylisoleucinol (4) and borane gives (5)-chlorohydrin (5), which is readily transformed to (S)- 

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Oxazaborolidines derived from proline (3) (see a,a-Diphenyl-2-pyrrolidinemetha not) and valine (1 R = i-Pr) (see 2-Amino-3-methyl-1,1-diphenyl-1-butanol) have received the most attention. 

In gleicher cheraischer Ausbeute, jedoch mit einer optischen Ausbeute von 76%, laBt sich Acetophenon-(O-methyl-oxim) mit Lithium-alanat in Gegenwart eines aus Diboran und (S)-2-Amino-3-methyl-l,l-diphenyl-butanol gebildeten Boran-Adduktes zu (S)-l-Amino-1-phenyl-ethan reduzieren2. 

Enantioselective reduction of ketones.1 The ability of diborane in combination with the vic-amino alcohol (S)-2-amino-3-methyl-l,l-diphenyl-l-butanol (12, 31) to effect enantioselective reduction of alkyl aryl ketones involves formation of an intermediate chiral oxazaborolidine, which can be isolated and used as a catalyst for enantioselective borane reductions (equation I). 

ASYMMETRIC REDUCTION OF KETONES (S)-(—)-2-Amino-3-methyl-1,1 -diphenyl-butane- 1 -ol. (S)-4-Anilino-3-methylamino-1 -butanol. 2,2-Dihydroxy-1,1 -binaphthyl. 

Related Reagents. 2-Amino-3-methy 1-1,1-diphenyl-1-butanol Ephedrine-borane Norephedrine-Borane Tetrahydro-1-methyl-3,3-diphenyl- l/f,3/f-pyrrolo[ 1,2-c] [ 1,3,2]oxaz aborole. 

Enantioselective Reduction of Imines and Ketoxime O-Ethers. In addition to the reduction of prochiral ketones, chiral oxazaborolidines have been employed as enantioselective reagents and catalysts for the reduction of imines (eq 11) and ketoxime O-ethers (eq 12) - to give chiral amines. It is interesting to note that the enantioselectivity for the reduction of ketoxime O-ethers is opposite that of ketones and imines. For more information, see 2-Amino-3-methyl-l,l-diphenyl-I-butanol. 

ASYMMETRIC REDUCTIONS 2,2 -Dihydroxy-1, l -binaphthyl-Lithium aluminum hydride. (2S,3RM+)-4-Dimethyl-amino-3-methyl-l,2-diphenyl-2-butanol. Lithium aluminum hydride-(-)-N-Methyiephedrine. B-(3)-oi-Pinanyl-9-borabicyclo[3.3.1 ]nonane. (S)-2-(2,6-Xylidinomethyl)pyrrolidine. 

A variety of amino alcohols have been examined as modifiers for lithium aluminum hydride. The most effective are 2-dimethylamino-l-phenyl-l-propanol (A-methylephedrine) and ( + )-(2S,3/ )-4-dimethylamino-3-methyl-l,2-diphenyl-2-butanol (Darvon alcohol or Chirald). 

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