ChemInform Abstract: anti‐Selective Dihydroxylation Reactions of Monosubstituted and (E)‐Ester Conjugated Allylic Amines by Bulky Alkyl Groups.

Jeon, Jongho; Kim, So‐Hee; Lee, Jong Hyup; Oh, Joon Seok; Park, Doh Yeon; Kim, Young Gyu

doi:10.1002/chin.200939050

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“…The initial nitro-alcohols 6 resulted from the nitro-aldol reaction between 4 and PhSO2CH2NO2 were dehydrated in-situ to result in the phenylsulfonylnitroolefin intermediates 7, which underwent the intramolecular conjugate addition to yield the cyclized adducts 5. The excellent stereoselectivity (>20:1) for trans-oxazolidines 5 could be rationalized by the favored H-eclipsed conformation of 7 [27][28]. The slower reactivity by the isopropyl analog 4b (R = i-Pr) might be also explained from the proposed mechanism (Scheme 3).…”

Section: Resultsmentioning

confidence: 84%

Stereoselective Synthesis of Novel Bestatin Analogs

Seo¹,

Lee²,

Kim³

2015

Applied Chemistry for Engineering

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Two new analogs of bestatin were prepared from D-leucine and D-valine in a stereoselective and efficient way. An aminopeptidase inhibitor bestatin shows significant biological effects on immunomodulation and is marketed for the treatment of acute myelocytic leukemia. The key intermediates, trans-oxazolidine methyl esters 2a and 2b, were obtained with more than 20 to 1 stereoselectivity in a one-pot procedure by the three cascade reactions between N-hydroxymethyl protected α-amino aldehydes (4a and 4b) and phenylsulfonylnitromethane (PhSO2CH2NO2) and the following in-situ ozonolysis. Basic hydrolysis of 2a and 2b, and then the peptide coupling with L-Leu-OMe produced the protected derivatives of two new bestatin analogs, 3a and 3b, respectively. The new isobutyl and isopropyl analogs of bestatin (1a and 1b) were produced in overall 51% and 38% yields, respectively, with high stereoselectivity from the corresponding protected α-amino aldehydes 4 in a six-step process.

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Section: Resultsmentioning

confidence: 84%