21440-07-3

Upstream product

• 4816-82-4 N-[(4-methylphenyl)-sulfonyl]-L-aspartic acid 
• 98-59-9 p-toluenesulfonyl chloride 

Downstream Products

• 181770-37-6 (S)-4-Oxo-4-phenyl-2-(toluene-4-sulfonylamino)-butyric acid 
• 287111-81-3 (S)-1-benzyl-3-p-toluenesulfonylamino-2,5-pyrrolidinone 
• 184302-66-7 (S)-N,N-Dimethyl-4-oxo-4-phenyl-2-(toluene-4-sulfonylamino)-butyramide 
• 184303-10-4 (S)-2-[Methyl-(toluene-4-sulfonyl)-amino]-4-oxo-4-phenyl-butyric acid methyl ester 
• 184302-65-6 (S)-4-Oxo-4-phenyl-2-(toluene-4-sulfonylamino)-butyric acid tert-butyl ester 
• 184303-03-5 (S)-2-[Benzyloxycarbonylmethyl-(toluene-4-sulfonyl)-amino]-4-oxo-4-phenyl-butyric acid methyl ester 

Relevant academic research and scientific papers

Total syntheses of the spermine alkaloids (-)-(R,R)-hopromine and (±)-homaline

The diastereoselective synthesis of the spermine alkaloid (R,R)-hopromine (2) is described. The as yet unknown absolute configuration of naturally occurring (-)-hopromine (2) is (R,R) and was established by comparison of the reported specific rotation of the natural product with that of the synthetic one. Preparation of the characteristic bis-8-membered lactam scaffold was carried out by convergent build-up of basic chiral azalactam units 21a and 21b and subsequent iterative linking (Schemes 5 and 6). Key steps in the analogous syntheses of 4-alkyl-hexahydro-1,5-diazocin-2(1H)-ones 21a and 21b were the introduction of the unbranched alkyl side chains into their common precursor 14 via cuprate reaction and the Sb(OEt)3-assisted cyclization of the open-chain intermediates 20a and 20b, respectively (Schemes 3 and 4). The chiral iodoester 14 was prepared from commercially available (+)-L-aspartic acid (12). Based on the synthetic strategy developed for (R,R)-hopromine (2), a rapid access to the parent alkaloid homaline (1) in its (±)-form is given.

A practical synthesis of (2S,3R)-3-amino-2-methylpentanoic acid from L-aspartic acid

L-Aspartic acid by successive N-tosylation, anhydride formation, and reduction was converted into (3S)-3-(tosylamino)butano-4-lactone (4). Electrophilic methylation of 4, subsequent iodo-esterification and nucleophilic methylation, followed by saponification and deprotection, gave (2S,3R)-3-amino-2-methylpentanoic acid (2) with an ee of > 99%in seven steps and in an overall yield of 34%.

An enantiospecific synthesis of β-amino acids

L-Aspartic acid by regioselective modification of the α-carboxylic acid group, namely N-tosylation, anhydride formation, reduction, iodo-esterification, alkylation, and deprotection afforded a series of γ-alkyl β-aminobutyric acids of the R configuration (ee > 99%).