84570-47-8

Upstream product

• 193421-73-7 α-allylphenylglycine ethyl ester 
• 84570-48-9 (S)-2-Amino-2-phenyl-pent-4-enoic acid; hydrochloride 
• 142421-36-1 (RS)-2-amino-2-phenyl-4-pentenoic acid amide 
• 120902-62-7 2-allyl-2-phenylglycine methyl ester 
• 84570-31-0 (6S)-3,6-Dihydro-6-isopropyl-5-methoxy-3-phenyl-3-(2-propenyl)-2H-1,4-oxazin-2-on 
• 360074-81-3 (S)-2-allyl-2-phenylglycine methyl ester 
• 15206-55-0 methyl 2-oxo-2-phenylacetate 
• 159041-91-5 (Z)-methyl 2-(2-benzoylhydrazono)-2-phenylacetate 

Relevant academic research and scientific papers

Asymmetric allylation of α-ketoester-derived N-benzoylhydrazones promoted by chiral sulfoxides/N-oxides lewis bases: Highly enantioselective synthesis of quaternary α-substituted α-allyl-α-amino acids

Chiral sulfoxides/N-oxides (R)-1 and (R,R)-2 are effective chiral promoters in the enantioselective allylation of α-keto ester N-benzoylhydrazone derivatives 3a, 3b, 3c, 3d, 3e, 3f, 3g to generate the corresponding N-benzoylhydrazine derivatives 4a, 4b, 4c, 4d, 4e, 4f, 4g, with enantiomeric excesses as high as 98%. Representative hydrazine derivatives 4a, 4b were subsequently treated with SmI2, and the resulting amino esters 5a, 5b with LiOH to obtain quaternary α-substituted α-allyl α-amino acids 6a, 6b, whose absolute configuration was assigned as (S), with fundament on chemical correlation and electronic circular dichroism (ECD) data. 2013 Wiley Periodicals, Inc.

Stereoselective synthesis of 4-hydroxy-2-phenylproline framework

Highly diastereoselective (>20:1) bromo-lactonization of N-sulfonyl-2-allyl-2-phenylglycine methyl ester (11) was observed. Successive treatment of the chiral lactone with MeONa gave the desired (2S,4R)-4-hydroxy-2- phenylproline derivative in high yield without erosion of the diastereoselectivity. The starting chiral non-racemic compound (5) was prepared from the racemic 2-phenylglycine using a classical kinetic resolution (crystallization), an asymmetric phase transfer alkylation, and an enzyme-catalyzed kinetic resolution.

A convenient synthesis of protected (R)-α-phenylproline derivatives using the Mitsunobu reaction

Boc-(R)-α-phenylproline ethyl ester 1 was prepared in good yield starting from racemic phenylglycine. Condensation of phenylglycine ethyl ester with benzaldehyde furnished N-benzylidene phenylglycine ethyl ester which was allylated under phase transfer catalysis conditions. After acidic hydrolysis, tile resulting α-allylphenylglycine ethyl ester was enzymatically resolved using PLE. Hydroboration and oxidation of the double bond, Boc-protection and subsequent ring closure using the Mitsunobu reaction protocol gave rise to Boc-(R)-α-phenylproline ethyl ester.

Enzymatic resolution of α,α-disubstituted α-amino acid esters and amides

The scope and limitations of the enzymatic resolution of α,α-disubstituted α-amino acid amides by an amino acid amidase from Mycobacterium neoaurum and of the corresponding ethyl esters with Pig liver esterase (PLE) have been studied. Moderate enantiomeric excesses were obtained with PLE, with only a narrow substrate specificity. Mycobacterium neoaurum on the contrary yields a broad range of S-α,α-disubstituted α-amino acids 1 and the corresponding R-amides 2.