171007-26-4

Upstream product

• 7065-46-5 3,3-dimethylbutanoic acid chloride 
• 171007-18-4 3-(3'-indolyl)-(2S)-(N-methylamino)-1,1-di(4''-methylphenyl)-1-propanol 
• 526-31-8 L-abrine 
• 32164-04-8 (S)-(+)-N_b-methyltryptophan methyl ester 

Relevant academic research and scientific papers

Chiral ligands derived from abrine. Part 6: Importance of a bulky N-alkyl group in indole-containing chiral β-tertiary amino alcohols for controlling enantioselectivity in addition of diethylzinc toward aldehydes

A number of chiral β-amino alcohols possessing a 3-indolylmethyl group have been synthesized from the alkaloid, (S)-abrine and elucidated for potency in the catalytic enantioselective ethylation of PhCHO with Et2Zn. In general, the secondary amines 15a-d bearing a dialkylhydroxymethyl group induced (R)-1-phenyl-1-propanol, whereas 15e-g and 18 bearing a diarylhydroxymethyl group favored the (S)-enantiomer. In contrast, the β-tertiary amino alcohols 20b-d and 21 produced (R)-1-phenyl-1-propanol, regardless of the substituents at the carbon bearing the hydroxy group. Enantiomeric excess of 87.5% was obtained for (R)-1-phenyl-1-propanol using ligand 21 as the promoter. Eleven substituted benzaldehydes and naphthaldehydes were examined for enantioselective ethylation by using 21 and the chiral alcohols were obtained in 93-97% ee, except for o-BrC6H4CHO and p-Me2NC6H4CHO. Excellent enantioselectivity was also observed in the ethylation of cyclohexanecarboxaldehyde (94.8% ee) and 2-thiophenecarboxaldehyde (94.9% ee) by using catalytic 21. The anti 5/4/4-fused tricyclic TS I was proposed to rationalize the asymmetric induction. The diethylhydroxymethyl and N-2-t-butylethyl groups are believed to enforce the preference for the anti-TS(R) I and it results in high enantioselectivity. Copyright (C) 2000 Elsevier Science Ltd.

Chiral ligands derived from abrine. 1. Synthesis of sec- and tert-β-amino alcohols and catalysis for enantioselective addition of diethylzinc toward aromatic aldehydes

A number of indole-containing chiral β-amino alcohols 3a-d and 9a-e have been synthesized from the alkaloid, Abrine (1) readily available from seeds of Abrus precatorius collected in Yunnan Province of China. Catalysis of the synthesized chiral ligands for the addition of diethylzinc toward benzaldehyde was examined. A significant role of the substituent(s) in the catalyst on the degree of asymmetric induction was uncovered. Enantiomeric excess of the product up to 94.2% was recorded.