enantioselective Negishi cross‐coupling reaction, and the first arylation of α‐halo esters with arylzinc halides, are disclosed. Employing a cobalt‐bisoxazoline catalyst, various α‐arylalkanoic esters were synthesized in excellent enantioselectivities and yields (up to 97 % ee and 98 % yield). A diverse range of functional groups, including ether, halide, thioether, silyl, amine, ester, acetal, amide, olefin
Trimethylsilyl chloride promoted synthesis of α-branched amines by nucleophilic addition of organozinc halides to nitrones
作者:Ying Fu、Yanhua Liu、Yaojuan Chen、Helmut M. Hügel、Minzhu Wang、Danfeng Huang、Yulai Hu
DOI:10.1039/c2ob26202a
日期:——
general procedure for the nucleophilicaddition of organozinc halides with nitrones in the presence of trimethylsilyl chloride has been developed. Trimethylsilyl chloride was found to be both an indispensable reaction promoter and a ready hydroxylamine protective agent in these reactions. The produced O-(trimethylsilyl)hydroxylamines can be easily reduced into corresponding amines just by a zinc–copper
Synthesis of Cyclopentenones with C4-Quaternary Stereocenters via Stereospecific [3,3]-Sigmatropic Rearrangement and Applications in Total Synthesis of Sesquiterpenoids
作者:Weiping Zhou、Arnaud Voituriez
DOI:10.1021/jacs.1c07966
日期:2021.10.27
A cationic gold(I)-catalyzed asymmetric [3,3]-sigmatropic rearrangement of sulfonium leads after cyclization to cyclopentenones with a C4-quaternary stereocenter. Starting with simple vinyl sulfoxides and propargyl silane, numerous compounds were isolated with moderate to good yields and excellent enantiomeric excesses (26 examples). The application of this simple methodology allowed the efficient
锍的阳离子金 (I) 催化不对称 [3,3]-σ 重排在环化后生成具有 C4-季立体中心的环戊烯酮。从简单的乙烯基亚砜和炔丙基硅烷开始,以中等至良好的收率和优异的对映异构体过量分离了许多化合物(26 个实例)。应用这种简单的方法可以有效地合成五种天然倍半萜类化合物,包括 enokipodin A 和 B、hitoyopodin A、lagopodin A 和 isocuparene-3,4-diol。
Nickel-catalyzed enantioselective arylation of pyridine
作者:J. Patrick Lutz、Stephen T. Chau、Abigail G. Doyle
DOI:10.1039/c6sc00702c
日期:——
We report an enantioselective Ni-catalyzed cross coupling of arylzinc reagents with pyridinium ions formed in situ from pyridine and a chloroformate. This reaction provides enantioenriched 2-aryl-1,2-dihydropyridine products that can be elaborated to numerous piperidine derivatives with little or no loss in ee. This method is notable for its use of pyridine, a feedstock chemical, to build a versatile
enantioselective synthesis of (R)‐cinacalcet with 99% enantiomericexcesses (ee) has been achieved. The main strategies of the approach include a gram‐scale cobalt‐catalysed asymmetric cross‐coupling of racemic ester with arylzinc reagent, Hoffman‐type rearrangement of acidamide, the amidation of chiral amine, and improving the ee of chiral amide from 87% to 99% via recrystallization.