<i>S</i>-((Phenylsulfonyl)difluoromethyl)thiophenium Salts: Carbon-Selective Electrophilic Difluoromethylation of β-Ketoesters, β-Diketones, and Dicyanoalkylidenes
S‐((Phenylsulfonyl)difluoromethyl)thiopheniumsalts were designed and prepared by a triflic acid catalyzed intramolecular cyclization of ortho‐ethynyl aryldifluoromethyl sulfanes. The thiopheniumsalts were found to be efficient as electrophilic difluoromehtylating reagents for introduction of a CF2H group to sp3‐hybridized carbon nucleophiles such as of β‐ketoesters and dicyanoalkylidenes. The (p
S -((苯磺酰基)二氟甲基)噻吩盐是通过三氟甲磺酸催化邻乙炔基芳基二氟甲基硫烷的分子内环化反应而设计和制备的。发现噻吩盐作为将CF 2 H基团引入sp 3杂交的碳亲核试剂(如β-酮酸酯和二氰基亚烷基)的亲电子二氟甲基化试剂非常有效。的(苯磺酰基)二氟甲基可容易地转化为CF 2温和反应条件下小时。在双(金鸡纳)生物碱的存在下也实现了对映选择性亲电二氟甲基化。
Phosphine-Catalyzed (3 + 2)/(3 + 2) Sequential Annulation of γ-Vinyl Allenoates: Access to Fused Carbocycles
作者:Jiaxu Feng、Yingying Chen、Wenhui Qin、You Huang
DOI:10.1021/acs.orglett.9b04176
日期:2020.1.17
The first (3 + 2)/(3 + 2) sequential annulation of γ-vinyl allenoates with alkylidenemalononitriles enabled by phosphine catalysis has been reported. A broad range of structurally dense tetra- and penta-substituted bicyclic[3,3,0]octene derivatives, containing a quaternary center and three sequential stereogenic center, were synthesized in good to excellent yields. In this approach, three new C-C bonds
Enantioface-differentiating epoxidation of alkylidenemalononitriles with molecular oxygen, catalyzed by chiral tertiary amines.
作者:KATSUMI NANJO、KUNIO SUZUKI、MINORU SEKIYA
DOI:10.1248/cpb.29.336
日期:——
The present paper describes the enantioface-differentiaing epoxidation of alkylidenemalononitriles with molecular oxygen, catalyzed by chiral tertiary amines. In the light of the by-product formation, the reaction path was concluded to involve intermolecular nucleophilic attack of a hydroperoxide intermediate catalyzed by a chiral tertiary amine. A similar epoxidation was demonstrated with cumylhydroperoxide in the presence of nicotine.
The asymmetric vinylogous Mannich reaction of dicyanoalkylidenes with α-amido sulfones under phase-transfer conditions
作者:Barbara Niess、Karl Anker Jørgensen
DOI:10.1039/b702172k
日期:——
The stereoselective vinylogous Mannich reaction of dicyanoalkylidenes underphase-transfer catalytic conditions utilizing stable alpha-amido sulfones as imine precursors is presented; a rigid pyrrolidinium salt acts as the phase-transfer catalyst, giving access to the amino alkylated products in generally good yield and up to 95% ee.