AbstractTreatment of a titanatrane complex with trimethylsilyl chloride and magnesium powder in tetrahydrofuran generated a low‐valent titanium species. This species catalyzed the radical ring opening of epoxides and oxetanes to produce the corresponding less substituted alcohols. The reagent also catalyzed the deallylation and depropargylation of allylic and propargylic ethers, respectively, to provide the parent alcohols.magnified image
Nucleophilic Difluoromethylation of Epoxides with PhSO(NTBS)CF<sub>2</sub>H by a Preorganization Strategy
作者:Xiao Shen、Qinghe Liu、Tao Luo、Jinbo Hu
DOI:10.1002/chem.201402506
日期:2014.5.26
synthesis of β‐monofluoromethyl alcohols by nucleophilic monofluoromethylation of epoxides, the synthesis of β‐difluoromethyl alcohols by nucleophilicdifluoromethylation of epoxides still remains a challenge. Herein, studies on tackling this problem with PhSO(NTBS)CF2H (2; TBS=tert‐butyldimethylsilyl) are reported. The preorganization of 2 and epoxides with BF3⋅Et2O was found to be crucial for the
A practical route from oxetane or thietane to γ‐(thio)butyrolactone via solvated‐proton‐assisted cobalt‐catalyzed carbonylative ring expansion under syngas atmosphere has been established. A wide variety of γ‐(thio)butyrolactones can be afforded in good to excellent yields. The versatility of this method has been well demonstrated in the synthesis of intermediates towards the natural product Arctigenin
Highly Regioselective Cleavages and Iodinations of Cyclic Ethers Utilizing SmI<sub>2</sub>
作者:Doo Won Kwon、Yong Hae Kim、Kieseung Lee
DOI:10.1021/jo020179r
日期:2002.12.1
Various functionalized cyclicethers such as oxiranes, oxetanes, and tetrahydrofurans have been prepared, and the regiochemistry of their ring opening with samarium diiodide and acyl chloride or anhydride has been investigated. Alkyl-substituted oxetane 5 and tetrahydrofurans 1 and 2 show almost no regioselectivity. However, high regioselectivities from the branched cyclicethers (3, 8, 9, and 10) containing
1-(Trifluoromethyl)vinylation via Oxirane or Oxetane Ring-Opening: A Facile Synthesis of 4- or 5-Hydroxy-Functionalized 2-Trifluoromethyl-1-alkenes
作者:Junji Ichikawa、Ryo Nadano
DOI:10.1055/s-2005-918413
日期:——
Introduction of a 1-(trifluoromethyl)vinyl group has been accomplished by the reaction of thermally unstable 1-(trifluoromethyl)vinyllithium (1) with strained cyclic ethers. Treatment of 2-bromo-3.3.3-trifluoropropene with butyllithium generates 1. which in turn reacts with several oxiranes or an oxetane at -100 °C in the presence of BF 3 .OEt 2 to afford the corresponding 2-trifluoromethyl- -1-alkenes