Fast and Highly Chemoselective Alkynylation of Thiols with Hypervalent Iodine Reagents Enabled through a Low Energy Barrier Concerted Mechanism
作者:Reto Frei、Matthew D. Wodrich、Durga Prasad Hari、Pierre-Antoine Borin、Clément Chauvier、Jérôme Waser
DOI:10.1021/ja5083014
日期:2014.11.26
Nevertheless, general methods to access these compounds are lacking. In this article, we describe the mechanism and full scope of the alkynylation of thiols using ethynyl benziodoxolone (EBX) hypervalent iodine reagents. Computations led to the discovery of a new, three-atom concerted transition state with a very low energy barrier, which rationalizes the high reaction rate. On the basis of this result
Regio‐ and stereoselective addition of a silyl‐substituted alkynyl sulfide to various terminal alkynes proceeds in the presence of a palladium catalyst to give (Z)‐1‐thio‐1,3‐enynes, which are useful building blocks for the synthesis of polysubstituted 1,3‐enynes. Addition to internal alkynes also takes place under solvent‐free conditions (see scheme).
Highly Regioselective Hydrosilylation of Unsymmetric Alkynes Using a Phenylthio Directing Group
作者:Kuan-Hsun Huang、Minoru Isobe
DOI:10.1002/ejoc.201402577
日期:2014.8
Cobalt-assisted hydrosilylation of acetylenes is particularly interesting in organic synthesis since alkynyl group functionalization can give way to more useful substructures. This study aims to answer the general question of how to control hydrosilylationregioselectivity with unsymmetric alkynyl groups. Cobalt-catalyzed hydrosilylation is highlyregioselective with alkyl-phenylthio-acetylenes affording
A heterogeneous copper-catalyzed direct oxidative cross-dehydrogenativecoupling of terminalalkynes with thiols was achieved in DMSO at 70 °C in the presence of an MCM-41-supported bidentate nitrogen copper(I) complex [MCM-41-2N-CuCl] and K2CO3 under an atmosphere of O2, yielding selectively a variety of alkynyl sulfides in good to excellent yields. This heterogeneous copper catalyst can be easily
在MSO-41负载的双齿氮铜(I)络合物[MCM-41-2N-CuCl]的存在下,在DMSO中于70°C的条件下,末端炔烃与硫醇的异质铜催化直接氧化交叉脱氢偶联反应和在O 2气氛下的K 2 CO 3,以良好至优异的产率选择性地产生各种炔基硫化物。该多相铜催化剂可通过简单的过滤容易地回收并循环10次而活性没有降低。
Copper-Catalyzed Extended Pummerer Reactions of Ketene Dithioacetal Monoxides with Alkynyl Sulfides and Ynamides with an Accompanying Oxygen Rearrangement
and ynamides provided a wide variety of γ,γ‐disulfanyl‐β,γ‐unsaturated carbonyl compounds with an accompanying oxygen rearrangement. The products can be easily converted into 1,4‐dicarbonyl compounds and substituted heteroaromatics. DFT calculations and mechanistic experiments revealed a new interesting stepwise addition/oxygen rearrangement mechanism.