Synthesis of Polysubstituted γ‐Butenolides via a Radical Pathway: Cyclization of α‐Bromo Aluminium Acetals and Comparison with the Cyclization of α‐Bromoesters at High Temperature
作者:Romain Bénéteau、Carole F. Despiau、Jean‐Christophe Rouaud、Anne Boussonnière、Virginie Silvestre、Jacques Lebreton、Fabrice Dénès
DOI:10.1002/chem.201501294
日期:2015.8.3
α‐bromoesters derived from propargyl alcohols by a one‐pot reaction involving the radicalcyclization of α‐bromo aluminium acetals, followed by the oxidation of the resulting cyclic aluminium acetals in an Oppenauer‐type process and migration of the exocyclic CC bond into the α,β‐position. Comparison with the direct cyclization of α‐bromoesters at high temperature and under high dilution conditions is described
Synthesis and determination of enantiomeric excesses of non-racemic tert-thiols derived from chiral secondary α-mercaptocarboxylic acids
作者:Bert Strijtveen、Richard M. Kellogg
DOI:10.1016/s0040-4020(01)87682-1
日期:1987.1
optically active without employment of a chiral auxiliary. Their enantiomericexcesses were determined by esterification, conversion to diasterecomeric phosphonodithioates on reaction with-31CH3-POCl2, followed by integration of the well separated proton-decoupled P NMR signals. This is apparently the first example of enantiomeric excess determinations of chiral tertiary thiols.
Efficient Synthesis of (2<i>S</i>,3<i>S</i>)-2-Ethyl-3-methylvaleramide Using (1<i>S</i>,2<i>S</i>)-Pseudoephedrine as a Chiral Auxiliary
作者:Bin-Feng Li、Robert M. Hughes、Jackie Le、Kevin McGee、Donald J. Gallagher、Raymond S. Gross、David Provencal、Jayachandra P. Reddy、Peng Wang、Lev Zegelman、Yuxin Zhao、Scott E. Zook
DOI:10.1021/op800260j
日期:2009.5.15
An efficient and scaleable synthesis of (2S,3S)-2-ethyl-3-methylvaleramide (1) has been developed starting from inexpensive and readily available l-isoleucine. The key step in this process is an asymmetric alkylation using (1S,2S)-pseudoephedrine as a chiralauxiliary. A practical procedure was developed to remove the sterically hindered pseudoephedrineauxiliary from the amide. The process consists
Absolute configuration of the four stereoisomers of valnoctamide (2-ethyl-3-methyl valeramide), a potentially new stereospecific antiepileptic and CNS drug
patients. The purpose of this paper is to assign the absoluteconfiguration of the four VCD stereoisomers and to describe the stereoselective synthesis used to prepare two-key VCD stereoisomers. We have synthesized two out of the four stereoisomers, with high diastereomeric excess, by two different synthetic methods. In both methods the (S) configuration at C-3 of VCD was fixed by synthesizing (S)-3-methyl
Diastereoselective Synthesis of the Acyl Side-Chain and Amino Acid (2<i>S</i>,3<i>R</i>)-3-Hydroxy-3-Methylproline Fragments of Polyoxypeptin A
作者:Tao Ye、Zhiyong Chen
DOI:10.1055/s-2005-918924
日期:——
Synthesis of the acyl side-chain and amino acid (2S,3R)-3-hydroxy-3-methylproline units of the potent depsipeptide polyoxypeptin A, is described. Key intermediates were secured via diastereoselective addition involving a homoenolateion and allylation of an aminoketone, respectively.
描述了强效缩肽聚氧肽素 A 的酰基侧链和氨基酸 (2S,3R)-3-羟基-3-甲基脯氨酸单元的合成。关键中间体通过非对映选择性加成获得,分别涉及同烯醇化物离子和氨基酮的烯丙基化。