Alkylidenesilacyclopropanes Derived from Allenes: Applications to the Selective Synthesis of Triols and Homoallylic Alcohols
作者:Kay M. Buchner、Timothy B. Clark、Janice M. N. Loy、Thong X. Nguyen、K. A. Woerpel
DOI:10.1021/ol900456v
日期:2009.5.21
transfer to allenes. Oxasilacyclopentanes derived from allenes were prepared with high regio- and diastereoselectivity by a two-step, one-flask silacyclopropanation/carbonyl insertion reaction. Triols and homoallylic alcohols were formed diastereoselectively by functionalizing the oxasilacyclopentanes. An optically active allene (>98% ee) was utilized to synthesize an enantiopure homoallylic alcohol in 96%
几种亚烷基硅杂环丙烷是通过银介导的甲硅烷基转移到丙二烯来制备的。通过两步、单烧瓶硅杂环丙烷化/羰基插入反应,以高区域选择性和非对映选择性制备了衍生自丙二烯的氧硅杂环戊烷。通过对氧硅杂环戊烷进行官能化,非对映选择性地形成三醇和高烯丙醇。光学活性丙二烯 (>98% ee) 用于合成 96% ee 的对映纯高烯丙醇。
Rhodium(III)-Catalyzed Directed C–H Dienylation of Anilides with Allenes Leads to Highly Conjugated Systems
allenylation, allylation, and annulation reactions. The outcome is governed by both the reactivity of the allene and the formation and stability of the organometallic intermediate. An efficient Rh(III)-catalyzed, weakly coordinating group-directed dienylation of electronically unbiased allenes is developed using an N-acyl amino acid as a ligand. Further elaboration of the dienylated products to construct
Carbocupration/Zinc Carbenoid Homologation and β-Elimination Reactions for a New Synthesis of Allenes − Application to the Enantioselective Synthesis of Chiral Allenes by Deracemization of sp3-Organometallic Derivatives
作者:Jos P. Varghese、Irena Zouev、Lionel Aufauvre、Paul Knochel、Ilan Marek
straightforward carbocupration/zinc homologation/β-elimination reaction sequence allows the one-pot synthesis of polysubstituted allenes from acetylenic sulfoxides in excellent isolated chemical yields. Secondary zinccarbenoids were used for the homologation reaction, and so a new synthesis of 1,1-diiodoalkanes is described. This methodology also allows the synthesis of chiral allenes through thermodynamic
Cyanoesterification of 1,2-Dienes: Synthesis and Transformations of Highly Functionalized α-Cyanomethylacrylate Esters
作者:Yoshiaki Nakao、Yasuhiro Hirata、Tamejiro Hiyama
DOI:10.1021/ja0606834
日期:2006.6.1
found to effect regioselective addition of cyanoformate esters across 1,2-dienes, giving rise to 3-alkoxycarbonyl-3-butenenitriles. Functional groups such as cyano, protected hydroxyl, and amino groups in the 1,2-diene substrates are tolerated. Isomerization of the initial products to thermodynamically more stable isomers takes place possibly through further oxidative addition of the C-CN bond of
Palladium-Catalyzed Chemoselective Allylic Substitution, Suzuki-Miyaura Cross-Coupling, and Allene Formation of Bifunctional 2-B(pin)-Substituted Allylic Acetate Derivatives
作者:Byeong-Seon Kim、Mahmud M. Hussain、Nusrah Hussain、Patrick J. Walsh
DOI:10.1002/chem.201402353
日期:2014.9.8
of organic synthesis is the control of chemoselectivity to enable the selective formation of diverse structural motifs from a readily available substrate class. Presented herein is a detailed study of chemoselectivity with palladium‐based phosphane catalysts and readily available 2‐B(pin)‐substituted allylic acetates, benzoates, and carbonates. Depending on the choice of reagents, catalysts, and reaction