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
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。
An Efficient Method for the Synthesis of 2′,3′-Nonsubstituted Cycloalkane-1,3-dione-2-spirocyclopropanes Using (2-Bromoethyl)diphenylsulfonium Trifluoromethanesulfonate
An efficient and practical synthesis of 2',3'-nonsubstituted cyclohexane-1,3-dione-2-spirocyclopropanes using a sulfonium salt was achieved. The reaction of 1,3-cyclohexanediones and (2-bromoethyl)diphenylsulfonium trifluoromethanesulfonate with powdered K2CO3 in EtOAc at room temperature (r.t.) provided the corresponding spirocyclopropanes in high yields. The synthetic method was also applied to 1
The ring‐opening cyclization of 2′,3′‐nonsubstituted and 2′‐electron‐withdrawing group (EWG)‐substituted cyclohexane‐1,3‐dione‐2‐spirocyclopropanes was accomplished using iodide as a catalyst. The nonsubstituted derivatives afforded 3,5,6,7‐tetrahydro‐1‐benzofuran‐4(2H)‐ones in high yields in the presence of trimethylsilyl iodide at room temperature. The EWG‐substituted spirocyclopropanes, in turn, underwent
Lithium aluminium hydridereduction of 6,6-dimethylspiro[2.5]octane-4,8-dione in tetrahydrofuran gave cis- and trans-6,6-dimethylspiro[2.5]octane-4,8-diols. Almost the same ratio of cis: trans=1:2 was obtained with various substrate-reagent ratios. In the case of Meerwein-Ponndorf-Verly reduction, however, cis-diol was obtained almost exclusively. It is clear that the former reduction gave kinetically-controlled