Scalar Cross-Relaxation Detected in the NOESY Spectra of Oxazolidines and Thiazolidines
作者:Tharindi D. Panduwawala、Laia Josa-Culleré、Ilya Kuprov、Barbara Odell、Mark G. Moloney、Timothy D. W. Claridge
DOI:10.1021/acs.joc.6b00458
日期:2016.5.20
Anomalous cross-peaks observed in the NOESY spectra of 2,4-disubstituted thiazolidines and oxazolidines that cannot be attributed to classical dipolar NOE or chemical exchange peaks have been investigated experimentally and computationally and have been shown to arise from scalar cross-relaxation of the first kind. This process is stimulated by the relatively slow modulation of scalar couplings and
[EN] UNNATURAL AMINO ACIDS<br/>[FR] ACIDES AMINÉS NON NATURELS
申请人:UNIV BRISTOL
公开号:WO2018109496A3
公开(公告)日:2018-07-26
Complementary Syntheses of <i>N</i>,<i>O</i>-Protected-(<i>S</i>)-2-methylserine on a Multikilogram Scale
作者:Michael S. Anson、Hugh F. Clark、Paul Evans、Martin E. Fox、Jonathan P. Graham、Natalie N. Griffiths、Graham Meek、James A. Ramsden、Alastair J. Roberts、Shaun Simmonds、Matthew D. Walker、Matthew Willets
DOI:10.1021/op100299d
日期:2011.3.18
Two complementary and scalable approaches have been used to manufacture multikilogram quantities of N,O-protected-(S)-2-methylserine. The first approach uses a diastereomeric salt resolution of 2-methylserine methyl ester as the (1S)-(+)-camphorsulfonate salt, and was used to rapidly access 15 kg of (S)-3-tert-butoxycarbonyl-2,2,4-trimethyl-1,3-oxazolidine-4-carboxylic acid with > 99% ee. The second approach involves a stereoselective enolate methylation of a chiral cyclic L-serine derivative under cryogenic conditions. The four-step telescoped process, starting from L-serine methyl ester, was used to manufacture 20 kg of (2R,4S)-2-tert-butyl-3-tert-butoxycarbonyl-4-methyl-1,3-oxazolidine-4-carboxylic acid in 52% overall yield and 98% ee. The advantages and disadvantages for scale-up of both approaches are discussed.
Synthetic Access to 3-Substituted Pyroglutamic Acids from Tetramate Derivatives of Serine, Threonine, <i>allo</i>-Threonine, and Cysteine
作者:Halima Bagum、Kirsten E. Christensen、Miroslav Genov、Alexander Pretsch、Dagmar Pretsch、Mark G. Moloney
DOI:10.1021/acs.joc.9b01432
日期:2019.8.16
A general route which provides direct access to pyroglutamates from tetramates, making use of Suzuki coupling on an enol mesylate, followed by reduction, is reported. This work permits direct scaffold hopping from tetramate to substituted pyroglutamates. Some compounds in the library showed modest antibacterial activity against Gram-positive bacteria.
α-alkylation of serine with self-reproduction of the center of chirality
作者:Dieter Seebach、Johannes D. Aebi
DOI:10.1016/s0040-4039(01)81227-2
日期:1984.1
The lithiumenolate 6 of methyl (2R,4S)-2--butyl-3-formyl-oxazolidine-4-carboxylate (4b) derived from (s)-(+)-serine can be generated with LDA in THF solution at −75°C. Alkylations (→ 9) and hydroxyalkylations (→ 10, 11) occur preferentially (>95:5) from the Re-face of the donor center (relative topicity lk). This stereochemical course is derived from the absolute configuration of 2-deuterio- and 2-methyl-serine