- Asymmetric Synthesis of Optically Active threo- and erythro-Pyrrolidinylbenzyl Alcohol by the Highly Stereospecific Arylation of (S)-Proline and the Subsequent Highly Diastereoselective Reduction of the α-Amino Ketone
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Optically active α-amino phenyl ketones in 92-94percent enantiomeric excess (e.e.) were obtained from the stereospecific arylation of (S)-proline or its derivatives by Friedel-Crafts reaction of by Grignard reaction.The subsequent complementary diastereoselective reductions of the α-amino ketone afforded respectively (S)- and (R)-α-benzyl alcohol in 93-100percent e.e. and in 100percent diastereoisomeric excess.The stereochemical course of the reduction of the α-amino ketone is discussed.
- Ookawa, Atsuhiro,Soai, Kenso
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p. 1465 - 1472
(2007/10/02)
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- Catalytic Asymmetric Induction. Highly Enantioselective Addition of Dialkylzincs to Aldehydes Using Chiral Pyrrolidinylmethanols and Their Metal Salts
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A series of chiral pyrrolidinylmethanols were synthesized from (S)-proline.Optically active secondary alcohols (R and S enantiomers, respectively) in up to 100percent enantiomeric excess (ee) were obtained in high yields from the enantioselective addition of dialkylzincs to aldehydes catalyzed by 2-5 mol percent of chiral pyrrolidinylmethanols.The sense of the asymmetric induction and the degrees of enantioselectivities were highly dependent on the structure of the catalysts. (+)-DPMPM (3, tertiary amino tertiary alcohol) catalyzed the reaction of aryl, α,β-unsaturated, and aliphatic aldehydes to afford (S) alcohols in high ee's.When the lithium salt of 3 was employed as catalyst in the reactions of aryl and α,β-unsaturated aldehydes, the ee's of (S) alcohols reached 100percent.On the other hand, (-)-erythro-PNPM (10, tertiary amino secondary alcohol) afforded (R) alcohols in high ee (100percent ee).The steric course of the reaction is discussed.
- Soai, Kenso,Ookawa, Atsuhiro,Kaba, Tatsuya,Ogawa, Kazuo
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p. 7111 - 7115
(2007/10/02)
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- Highly Stereospecific Arylation Of (S)-Proline and Complementary Highly Diastereoselective Reduction of the α-Amino Ketone. Asymmetric Synthesis of (1S,2'S)- and (1R,2'S)-Phenyl(2'-pyrrolidinyl)methanol
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Both optically active threo- and erythro-phenyl(2'-pyrrolidinyl)methanol (93-100percent enantiomeric excess, 100percent diastereoisomeric excess) were synthesised from (S)-proline by a stereospecific arylation and the subsequent complementary diastereoselective reduction of the α-amino ketone.
- Soai, Kenso,Ookawa, Atsuhiro
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p. 412 - 413
(2007/10/02)
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