70872-38-7

Upstream product

• 108-24-7 acetic anhydride 
• 24164-73-6 methyl (S)-2-(benzyloxycarbonyl-methyl-amino)-3-phenylpropionate 
• 70893-31-1 methyl (Z)-2-(N-methylacetamido)-3-phenylacrylate 
• 186581-53-3 diazomethane 
• 3618-96-0 (S)-N-acetylphenylalanine 

Downstream Products

• 55260-07-6 N-methyl-N-acetyl-L-phenylalanine 

Relevant academic research and scientific papers

"One-pot" methylation of N-nosyl-α-amino acid methyl esters with diazomethane and their coupling to prepare N-methyl dipeptides

N-Nosyl-α-amino acid methyl esters are methylated quantitatively with diazomethane. After proper deprotection of the amino function by treatment with the reagent system mercaptoacetic acid/sodium methoxide, the obtained N-methyl amino acid methyl esters are coupled with N-Fmoe amino acid chlorides to afford the corresponding dipeptides. The obtained products do not show any detectable extent of racemization by 1H NMR and HPLC.

Exploring stereogenic phosphorus: Synthetic strategies for diphosphines containing bulky, highly symmetric substituents

Diphosphine ligands bearing highly symmetric, bulky substituents at a stereogenic P atom were prepared, exploiting established protocols, which include the use of chiral synthons such as 3,4- dimethyl-2,5-diphenyl-1,3,2-oxazaphospholidine-2-borane (3a) and phenylmethylchlorophosphine borane (10) and the enantioselective deprotonation of dimethylarylphosphine boranes. However, only (But)(Me)PCH2CH2P(But)Me (8a) could be prepared from 3a. The diphosphines (S,S)-1,2-bis-(mesitylmethylphosphino)ethane, ((S,S)-8b) and (S,S)-1,2- bis(9-anthrylmethylphosphino)ethane ((S,S)-8c), which contain 2,6-disubstituted aryl P-substituents, were prepared by Evans' sparteine-assisted enantioselective deprotonation of P(Ar)(Me)2(BH3) (Ar = mesityl or 9-anthryl), but the enantioselectivity did not exceed 37% ee. The asymmetrically substituted, methylene-bridged diphosphine (2R,4R)-(Ph)(CH3)PCH2P(Mes)(CH3) ((2R,4R)-12) (Mes = mesityl) was prepared by the newly developed stereospecific reaction of the enantiomerically pure chlorophosphine borane PCl(Ph)(Me)(BH3) (10) with the racemic, monolithiated dimethylmesitylphosphine borane P(Mes)(Me)(CH2Li)(BH3). Diastereomerically pure (2R,4R)-12 was obtained with 86% ee. The rhodium(I) derivatives [Rh(COD)(P-P)]BF4 containing the diphosphine ligands 8a, 8b, and 12, as well as the previously reported (S,S)-1,2-bis(1-naphthylphenylphosphino)ethane ((S,S)-8d), were prepared and tested in the enantioselective catalytic hydrogenation of acetamidocinnamates. The best catalytic result (98.6% ee) was obtained with [Rh(COD)(8d)]+ as catalyst and methyl Z-α-acetamidocinnamate as substrate. Some of the catalytic results are discussed in terms of the preferred conformations of the substituents at phosphorus, as calculated by molecular modeling.

Novel formation and crystal structure of 2-(2,2,2-trifluoroethylidene)-6-trifluoro-methyl-2,3-dihydro-4H-1,4-oxazin-3- ones from N-acetyl-N-alkyl-α-amino acids

The title compounds (2a-g) were formed from N-acetyl-N-alkyl-α-amino acids (1a-g) on treatment with trifluoroacetic anhydride in the presence of pyridine. The structure of the product (2a) was determined by single crystal X-Ray analysis.