73035-89-9

Upstream product

• 72953-35-6 ((S)-3,6-Dimethoxy-2,5-dimethyl-2,5-dihydro-pyrazin-2-yl)-phenyl-methanol 
• 72953-35-6 (6S,3R,7R)-3-<(Hydroxyphenyl)methyl>-2,5-dimethoxy-3,6-dimethyl-3,6-dihydropyrazin 
• 181874-01-1 trans-(S_S,2R,3S)-(+)-N-(p-toluenesulfinyl)-2-methyl-2-carbomethoxy-3-phenylaziridine 
• 591-51-5 phenyllithium 
• 291313-81-0 (4S,5R)-4-(hydroxymethyl)-4-methyl-5-phenyl-3-oxazolidin-2-one 
• 291313-72-9 (1R,7aS)-1-phenyl-5,5,7a-trimethyl-2,6-dioxa-4-azapentalen-3-one 
• 291313-71-8 (S)-N-(tert-butoxycarbonyl)-4-[(R)-1'-phenylcarbinol]-2,2,4-trimethyl-3-oxazolidine 
• 350479-90-2 (S,E)-N-benzylidene-4-methylbenzenesulfinamide 
• 100-52-7 benzaldehyde 

Downstream Products

• 120328-90-7 methyl (E)-N-benzylidenealaninate 

Relevant academic research and scientific papers

Asymmetric synthesis of all isomers of α-methyl-β-phenylserine

This report describes the synthesis of enantiomerically pure (2R,3R)-, (2R,3S)-, (2S,3S)- and (2S,3R)-2-amino-3-hydroxy-2-methyl-3-phenylpropanoic acids, four quaternary α-amino acids, using a stereodivergent synthetic route and starting from (S)- and (R)-N-Boc-N,O-isopropylidene-α-methylserinals. The key step involves the asymmetric Grignard additions to the above chiral aldehydes, in which high levels of asymmetric induction are observed. Copyright (C) 2000 Elsevier Science Ltd.

2-Methyl N-(p-toluenesulfinyl)aziridine-2-carboxylic acid: Asymmetric synthesis of α-methylphenylalanine and α-methyl-β-phenylserine

2-Substituted aziridine 2a, prepared from sulfinimine 1 via a Darzens-type condensation, undergoes a highly regio- and stereocontrolled ring-opening to give α-methylphenylalanine and α-methyl-β-phenylserine in high enantiomeric purity.

ENANTIOSELECTIVE SYNTHESIS OF NON-PROTEINOGENIC AMINO ACIDS VIA METALLATED BIS-LACTIM ETHERS OF 2,5-DIKETOPIPERAZINES

Bis-lactim ethers 1 of 2,5-diketopiperazines contain a chiral inducing center, an acidic CH-bond and two sites susceptible to hydrolysis.They react with BuLi to give Li compounds of type 4, 15, 29 or 32, which possess a prochiral C atom.They readily add electrophiles (such as alkylating agents or carbonyl compounds) with unusually high diastereoface differentiation.In many cases the d.e-value (d.e. = diastereomeric excess = asymmetric induction) of the adduct exceeds 95percent.On hydrolysis the adducts are cleaved liberating the chiral auxiliary (used to build up the bis-lactim ether 1) and the target molecules, the optically active amino acid methyl esters of type 8, 19, 25 or 36.The two amino acid esters are separable either by fractional distillation or (eventually after further hydrolysis to amino acids) by chromatography.Transition state models are discussed that could explain the exceptionally high asymmetric induction and the predictability of the induced configuration.

Asymmetric Syntheses via Heterocyclic Intermediates, X. - Enantioselective Synthesis of (2R)-2-Methylserines

Aldehydes and ketones react with the lithiated bislactim ether 3 of cyclo-(L-Ala-L-Ala) with 81 to >95percent asymmetric induction (d.e. = diastereomeric excess) at C-3; (R) configuration is formed predominantly. - A model concept for the asymmetric induction is proposed. - With aldehydes or unsymmetrical ketones C-7 of the adducts 6 becomes a chiral center, too. (R) configuration is induced here with d. e. 47 - 73percent.Hydrolysis of the addition products 6 (0.25 N HCl, room temperature) gives L-Ala-OCH3 and (2R)-2-methylserine methyl esters 7.Both compounds can be separated either at the ester stage by distillation or - if 7 is thermolabile - after further hydrolysis at the amino acid stage.