74936-96-2Relevant academic research and scientific papers
Mass Spectrometric Screening of Racemic Amine Catalysts for Enantioselective Michael Additions
B?chle, Florian,Fleischer, Ivana,Pfaltz, Andreas
, p. 2247 - 2254 (2015)
In extension of a concept of Lloyd-Jones, based on the combination of a racemic catalyst with a scalemic substrate, we have recently developed a method for determining the enantioselectivity of a chiral catalyst from its racemic form by mass spectrometric screening of a non-equal mixture of two mass-labeled quasi-enantiomeric substrates. After an initial proof of principle using palladium-catalyzed allylic substitution as test reaction, we report now the successful application of this approach to the screening of chiral amines as catalysts for the enantioselective Michael addition to α,β-unsaturated aldehydes. The results confirm that our method allows fast and reliable evaluation of chiral racemic catalysts. This opens up new possibilities for investigating catalyst structures that are not easily available in enantiomerically pure form.
Enantioselective ring expansion of prolinols: An efficient and short synthesis of 2-phenylpiperidin-3-ol derivatives and 3-hydroxypipecolic acids
Cochi, Anne,Burger, Benjamin,Navarro, Cristina,Pardo, Domingo Gomez,Cossy, Janine,Zhao, Yang,Cohen, Theodore
body text, p. 2157 - 2161 (2009/12/24)
A very short route to 2-phenylpiperidin-3-ol derivatives and 3-hydroxypipecolic acids is described. The approach uses two key steps: a one-pot reduction/Grignard addition sequence applied to alkyl proline esters and a ring expansion applied to the corresp
Enantioselective synthesis of 2,3-disubstituted piperidines from (S)- methylpyroglutamate
Calvez, Olivier,Chiaroni, Angele,Langlois, Nicole
, p. 9447 - 9450 (2007/10/03)
N-methoxy-N-methylamide derived from (S)-methylpyroglutamate was prepared in good yield and allowed the addition of Grignard reagents. Erythro (2S)-1-benzyl-2-hydroxybenzyl pyrrolidine obtained by this way was converted into (2S,3R)-1-benzyl-3-hydroxy-2-phenylpiperidine and its chloro analog.
Catalytic Asymmetric Induction. Highly Enantioselective Addition of Dialkylzincs to Aldehydes Using Chiral Pyrrolidinylmethanols and Their Metal Salts
Soai, Kenso,Ookawa, Atsuhiro,Kaba, Tatsuya,Ogawa, Kazuo
, p. 7111 - 7115 (2007/10/02)
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.
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
Ookawa, Atsuhiro,Soai, Kenso
, p. 1465 - 1472 (2007/10/02)
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.
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
Soai, Kenso,Ookawa, Atsuhiro
, p. 412 - 413 (2007/10/02)
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.
