Photorearrangement of Propargyl Bromide as a Probe to Study Propargylic and Allenic Radicals by Infrared Matrix Isolation Technique
摘要:
AbstractThe photolysis of propargyl bromide in Ar matrix to form allenyl bromide proceeded with a radical mechanism. The deuterium label study and radical scavenger were used to investigate the mechanism. Neither propargyl nor allenyl radical was trapped in Ar matrix at 8 K. The rates of propargyl and allenyl radicals coupled with bromo radical are significantly fast. The stability of propargyl and allenyl radicals is discussed.
Palladium catalyzed cyclization reactions of acetylenic lactams
作者:Willem F.J. Karstens、Marianne Stol、Floris P.J.T. Rutjes、Huub Kooijman、Anthony L. Spek、Henk Hiemstra
DOI:10.1016/s0022-328x(00)00935-9
日期:2001.4
Lactams and oxazolidinones containing a 3-butynyl side chain at the four- and the three-position, respectively, have been prepared by reductive alkylation of cyclicimides or by SN2′-substitution of bromopropadiene with highly functionalized enantiopure organozinc reagents. Treatment of these compounds with aryl halides and one vinyl bromide using Pd(PPh3)4 as a catalyst gives rise to a coupling-cyclization
内酰胺和恶唑烷酮分别在四个和三个位置上含有一个3-丁炔基侧链,是通过环酰亚胺的还原烷基化或用高度官能化的对映纯有机锌试剂对溴丙二烯进行S N 2'取代制得的。使用Pd(PPh 3)4作为催化剂,用芳基卤化物和一种乙烯基溴处理这些化合物会引起偶联环化反应,从而生成其中掺入了芳基或乙烯基部分的双环酰胺。值得注意的是,这些基团是立体选择性地顺式转移的关于氮亲核试剂到三键上。通过环化产物的晶体结构分析和NOE差光谱法已经获得了这种异常立体化学结果的结构证明。
Synthèse régiospécifique d'amines tertiaires à groupe secondaire bi-insaturé
作者:D. Mesnard、L. Miginiac
DOI:10.1016/0022-328x(89)85018-1
日期:1989.9
We describe the regiospecific preparation of tertiary amines with a symmetrical (or dissymmetrical) doubly unsaturated secondary group, by reaction of an allylic, vinylic or acetylenic organometallic derivative with a dialkylformamido acetal, a chlorinated iminium salt or an alkynyl aminoether.
the regio- and stereoselectivity of these reactions is discussed and compared to its role played in radical hydrosilylation and hydrogermylation reactions. Protocols developed to achieve the β-regioselective silylzincation of propargyl alcohol and the α-regioselective germylzincation of internal propargylic alcohols are particularly important, as they occur with trans stereoselectivity. For both procedures
Regio‐ and Diastereoselective Copper‐Catalyzed Carbomagnesiation for the Synthesis of Penta‐ and Hexa‐Substituted Cyclopropanes
作者:Yair Cohen、André U. Augustin、Laura Levy、Peter G. Jones、Daniel B. Werz、Ilan Marek
DOI:10.1002/anie.202102509
日期:2021.5.17
Despite the highly strained nature of cyclopropanes possessing three vicinal quaternary carbon stereocenters, the regio‐ and diastereoselective copper‐catalyzed carbomagnesiation reaction of cyclopropenes provides an easy and efficient access to these novel persubstituted cyclopropyl cores with a complete regio‐ and diastereoselectivity.
Application of an organozinc reagent derived from (S)-pyroglutamic acid: a formal synthesis of epibatidine
作者:Willem F.J. Karstens、Marinus J. Moolenaar、Floris P.J.T. Rutjes、Urszula Grabowska、W.Nico Speckamp、Henk Hiemstra
DOI:10.1016/s0040-4039(99)01808-0
日期:1999.12
A formal totalsynthesis of natural (−)-epibatidine has been developed. Key steps in the synthesis are a copper(I)-mediated coupling of an (S)-pyroglutamic acid-derived organozinc reagent with 1-iodo-3-trimethylsilyl-1-propyne and an N-acyl- or N-sulfonyliminium ion cyclization. Following this route, various N-protected hydroxylactams were converted into 7-azabicylo[2.2.1]heptane derivatives.