191337-25-4

Upstream product

• 2577-90-4 methyl (2S)-2-amino-3-phenylpropanoate 
• 98-74-8 4-Nitrobenzenesulfonyl chloride 
• 7524-50-7 methyl (2S)-2-amino-3-phenylpropanoate hydrochloride 

Downstream Products

• 191337-28-7 (S)-2-[(3-Methyl-but-2-enyl)-(4-nitro-benzenesulfonyl)-amino]-3-phenyl-propionic acid methyl ester 
• 610800-50-5 (S)-methyl 2-(N-methyl-4-nitrophenylsulfonamido)-3-phenylpropanoate 
• 73270-67-4 (S)-2-allylamino-3-phenyl-propionic acid methyl ester 
• 79638-37-2 Boc-(Nall)Phe-OH 
• 175207-89-3 (S)-2-(allyl-tert-butoxycarbonylamino)-3-phenylpropionic acid methyl ester 
• 292849-74-2 Boc-(Nall)Phe-(Nall)Gly-OEt 
• 2577-90-4 methyl (2S)-2-amino-3-phenylpropanoate 
• 3618-96-0 (S)-N-acetylphenylalanine 
• 51987-73-6 (S)-2-tert-butoxycarbonylamino-3-phenyl-propionic acid methyl ester 
• 15136-29-5 (S)-methyl 2-((S)-2-((tert-butoxycarbonyl)amino)-3-phenylpropanamido)propanoate 
• 13734-34-4 N-tert-butoxycarbonyl-L-phenylalanine 

Relevant academic research and scientific papers

DBU Catalysed Enantioselective Degradative Rearrangement: a Way to Tetrasubstituted 2-Aryl-2-Amino Esters

Herein we report a catalytic, easily scalable protocol for the enantioselective synthesis of Tetrasubstituted α-aryl-α-amino acid derivatives, using a biphasic system composed by catalytic DBU in DME and aqueous solutions of Na2CO3. Under very mild reaction conditions, without using metal or chiral additives, this heterogeneous system promotes the degradative rearrangement of functionalized N-aryl sulphonyl α-amino esters into the corresponding tetrasubstituted 2-aryl-2-amino esters, with high enantiomeric ratios (up to 97.5:2.5) and good yields (up to 95%). (Figure presented.).

PdII-Catalyzed Enantioselective C(sp3)?H Activation/Cross-Coupling Reactions of Free Carboxylic Acids

PdII-catalyzed enantioselective C(sp3)?H cross-coupling of free carboxylic acids with organoborons has been realized using either mono-protected amino acid (MPAA) ligands or mono-protected aminoethyl amine (MPAAM) ligands. A diverse range of aryl- and vinyl-boron reagents can be used as coupling partners to provide chiral carboxylic acids. This reaction provides an alternative approach to the enantioselective synthesis of cyclopropanecarboxylic acids and cyclobutanecarboxylic acids containing α-chiral tertiary and quaternary stereocenters. The utility of this reaction was further demonstrated by converting the carboxylic acid into cyclopropyl amine without loss of optical activity.

Synthesis of enantioenriched 1,2-trans-diamines using the borono-Mannich reaction with N-protected α-amino aldehydes

The three-component Petasis borono-Mannich reaction starting with easily accessible N-protected α-amino aldehydes produces efficiently and diastereoselectively 1,2-trans-diamines with an enantiomeric excess of up to 98%.

Palladium(II)-catalyzed enantioselective C(sp3)-H activation using a chiral hydroxamic acid ligand

An enantioselective method for Pd(II)-catalyzed cross-coupling of methylene β-C(sp3)-H bonds in cyclobutanecarboxylic acid derivatives with arylboron reagents is described. High yields and enantioselectivities were achieved through the development of chiral mono-N-protected α-amino-O- methylhydroxamic acid (MPAHA) ligands, which form a chiral complex with the Pd(II) center. This reaction provides an alternative approach to the enantioselective synthesis of cyclobutanecarboxylates containing α-chiral quaternary stereocenters. This new class of chiral catalysts also show promises for enantioselective β-C(sp3)-H activation of acyclic amides.

Control of 6-Exo and 7-Endo cyclizations of alkynylamides using platinum and bismuth catalysts

The rules of cyclization: Alkynylamides are regioselectively cycloisomerized into piperazin-2-one and 1,4-diazepan-2-one derivatives by using catalytic amounts of appropriate metal catalysts. A 6-exo-dig addition proceeds in the presence of Bi(OTf)3, while the 7-endo-dig addition occurs with PtCl2 for the same substrate. (see scheme; Ns=o- nitrobenzenesulfonyl, Ts=p-toluenesulfonyl, Cbz=benzyloxycarbonyl, DCE=dichloroethane) Copyright

"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.

Synthesis of cyclic dipeptides by ring-closing metathesis

Several cyclic dipeptides (4a-g and 9a-c) have been synthesized by 'amide-to-amide' cyclization of 2a-g and 8a-c, respectively, by means of ring-closing metathesis employing the Grubbs ruthenium catalyst. The influence of additives as well as the length of the amide substituent were studied. Best yields were obtained by cyclization in solution with either lithium fluoroacetate or α,α-dichlorotoluene as an additive.

Site-specific N-alkylation of peptides on the solid phase

A convenient approach, featuring a Mitsunobu reaction, is described for the introduction of an alkyl group at a specific amide function of a peptide on the solid phase. This 'site-specific alkylation' procedure is illustrated with an N-ethyl scan of Leu-enkephalin.

Derivatized oxopiperazine rings from amino acids

Two routes for the synthesis of derivatized oxopiperazines, which may act as constrained peptide mimics, are reported. The syntheses employ reductive amination and sulfonamide approaches for generating N-allylic amino acid ester derivatives and utilizing them for assembling the ring systems. An aspartame analog was prepared using this methodology.