Ring-Opening Cyclization of Spirocyclopropanes Using Sulfoxonium Ylides
作者:Yuta Onuki、Hisanori Nambu、Takayuki Yakura
DOI:10.1248/cpb.c20-00132
日期:2020.5.1
cyclohexane-1,3-dione-2-spirocyclopropanes using dimethylsulfoxonium methylide proceeded regioselectively to produce 2,3,4,6,7,8-hexahydro-5H-1-benzopyran-5-ones in good to high yields. The reactions of cycloheptane- and cyclopentane-1,3-dione-2-spirocyclopropanes could construct [7.6]- and [5.6]-fused ring systems. This reaction was also carried out using sulfoxonium ethylide, butylide, and benzylide
Metal-free intermolecular cyclopropanation between alkenes and iodonium ylides mediated by PhI(OAc)<sub>2</sub>·Bu<sub>4</sub>NI
作者:Jason Tao、Carl D. Estrada、Graham K. Murphy
DOI:10.1039/c7cc04859a
日期:——
A rapid, mild and metal-freeintermolecular cyclopropanation between iodonium ylides and alkene-containing substrates mediated by PhI(OAc)2·Bu4NI is reported. Iodonium ylides of cyclic and acyclic 1,3-dicarbonyls were reacted with a variety of mono-, di-, tri- and tetra-substituted alkenes of various structural types to give 29 cyclopropanes in up to 97% yield.
Inherent Reactivity of Spiro‐Activated Electrophilic Cyclopropanes
作者:Patrick M. Jüstel、Alexandra Stan、Cedric D. Pignot、Armin R. Ofial
DOI:10.1002/chem.202103027
日期:2021.11.17
Ring, ring! The reactivity of spiro-activated electrophilic cyclopropanes was studied by following the kinetics of their SN2-type ring-opening reactions with thiophenolate ions in DMSO at 20 °C. The experimentally determined second-order rate constants (k2) correlated linearly with Mayr nucleophilicities N, basicities (pKaH), and Hammett substituent constants of the thiophenolates, but parabolic Hammett
响铃,响铃!通过跟踪螺环活化的亲电环丙烷在 20 °C 的 DMSO 中与苯硫酚离子的 S N 2 型开环反应的动力学,研究了螺环活化的亲电环丙烷的反应性。实验确定的二阶速率常数 ( k 2 ) 与迈尔亲核性N 、碱度 (p K aH ) 和苯硫酚盐的哈米特取代基常数线性相关,但抛物线哈米特图揭示了对转变稳定性的不同亲电子依赖性影响州。
Ring-opening cyclization of spirocyclopropanes with stabilized sulfonium ylides for the construction of a chromane skeleton
Regioselective ring-opening cyclization of cyclohexane-1,3-dione-2-spirocyclopropanes with stabilized sulfoniumylides provided 2,3-trans-disubstituted 2,3,4,6,7,8-hexahydro-5H-1-benzopyran-5-ones in high yields without the formation of any isomers. The obtained product was readily converted into highly substituted chromane.
环己烷-1,3-二酮-2-螺环丙烷与稳定的硫鎓烷基化物的区域选择性开环环化提供了2,3-反式-二取代的2,3,4,6,7,8-六氢-5 H -1-苯并吡喃-高产率的5-ones,不形成任何异构体。所获得的产物易于转化为高度取代的苯并二氢吡喃。
Asymmetric induction in cyclopropanation with homogeneous and immobilized chiral metal β-diketonate catalysts
作者:Stephen A. Matlin、W. John Lough、Lam Chan、David M. H. Abram、Ziqing Zhou
DOI:10.1039/c39840001038
日期:——
Copper complexes of 3-trifluoroacetyl-(+)-camphor and two of its drivatives give high optical yields when used ascatalysts for the asymmetriccyclopropanation of styrene with 2-diazodimedone; an immobilised analogue of these homogeneouscatalysts retains high activity, is readily recovered, and has portential for recycling.