共查询到20条相似文献,搜索用时 15 毫秒
1.
A study of the free racinoal reaction of vinylcycloprelpane mediated by p-toluenesulfonyl chloride is described. 相似文献
2.
Jos Barluenga Gustavo P. Romanelli Lorenzo J. Alvarez-García Isidro Llorente Jos M. Gonzlez Esther García-Rodríguez Santiago García-Granda 《Angewandte Chemie (International ed. in English)》1998,37(22):3136-3139
Formation of polycyclic structures within a few minutes: The intramolecular cyclization of diynes, activated by a benzenesulfenyl substituent, upon reaction with IPy2BF4 proceeds as an efficient exo–endo coupling. A subsequent novel Friedel–Crafts-like ring closure provides the product [Eq. (1)]. Thus, intra- and intermolecular cyclizations can be carried out. 相似文献
3.
《中国化学快报》2020,31(7):1877-1880
N,N'-Disulfonylhydrazines have been proven to be the most reactive precursors of the sulfonyl radicals among all types of sulfonyl substituted hydrazines as early as half a century ago. However, the sulfonyl radicals generated from these compounds have not been used in organic synthesis except the simple self-dimerization synthesis of disulfones controlled by the “solvent-cage-effects”. In this article, N,N′-disulfonylhydrazines were introduced as new sulfonylating reagents and their combinations with NIS were disclosed as new iodosulfonylating reagents of alkynes. Finally, a highly efficient method for the synthesis of (E)-β-iodovinyl arenesulfones was developed by mixing an alkyne, a N,N′-disulfonyl-hydrazine and NIS in aqueous THF at room temperature for 5 min. 相似文献
4.
Christoph Rüchardt 《Angewandte Chemie (International ed. in English)》1970,9(11):830-843
An analysis of the relations between structure and reactivity in free-radical chemistry has shown that the usual interpretation of reactivities by means of the stability of the radicals involved is greatly simplified and often incorrect. The C? X bond energies of the alkanes and simple alkyl derivatives can be explained qualitatively by strain effects in the ground state on the basis of the VSEPR theory and nonbonding interactions. To be able to explain reactivities in free-radical chemistry, it is necessary to deduce information about the geometry of the transition states during free-radical formation from experimental measurements. The relations between structure and reactivity in free-radical chemistry are interpreted in terms of bond dissociation energies, as well as polar and steric effects. 相似文献
5.
E. Müller A. Rieker K. Scheffler A. Moosmayer 《Angewandte Chemie (International ed. in English)》1966,5(1):6-15
The paper describes the application and limitations of magnetic methods to the problems of free-radical chemistry (detection and quantitative investigation of the free-radical state, relationships between structure and free-radical formation, “distribution” of the unpaired electron, detection of mesomeric C, O, N, P, As, and Sn radicals, g-factors, triplet states, and hyperfine structure). The problem of the diradical is described, and the paper closes with a discussion of the “Selwood effect”. 相似文献
6.
Herbert C. Brown M. Mark Midland 《Angewandte Chemie (International ed. in English)》1972,11(8):692-700
In the few short years since the discovery that organoboranes undergo facile free-radical substitution, application of these reactions has become a major new area of synthetic utility. Organoboranes undergo a wide variety of free-radical reactions such as autoxidation to the alcohol or hydroperoxide, 1, 4 addition to α,β-unsaturated derivatives, addition to disulfides, and oxygen-induced radical coupling. It is evident that organoboranes constitute a versatile new source of free radicals and that these reactions can be readily controlled to give very clean syntheses. The application of these reactions will be discussed. 相似文献
7.
5-Sulfonamidopyrazoles were efficiently synthesized from terminal alkynes, sulfonyl azides and hydrozones. The sequential reaction involves a copper-catalyzed three-component reaction, a Lewis acid-catalyzed electrocyclic reaction and a dehydrogenation. 相似文献
8.
Ali Sharifi Hossein Farhangian Farshid Mohsenzadeh M. R. Naimi-Jamal 《Monatshefte für Chemie / Chemical Monthly》2002,133(2):199-204
Summary. Terminal alkynes, secondary amines, and formaldehyde undergo a Mannich reaction at room temperature in the presence of CuCl on Al2O3 without any organic solvent as reaction medium. The reaction can be promoted by microwave irradiation and is complete within
one minute.
Received May 2, 2001. Accepted (revised) June 25, 2001 相似文献
9.
Karl Griesbaum 《Angewandte Chemie (International ed. in English)》1970,9(4):273-287
In view of the growing importance of photochemically initiated reactions in industry, the use of free-radical additions of thiols to unsaturated compounds also seems promising. The present article is intended to demonstrate the possibilities and limitations of reactions of this type in organic synthesis. 相似文献
10.
Dr. Hai-Dong Xia Dr. Zhong-Liang Li Dr. Qiang-Shuai Gu Xiao-Yang Dong Jia-Heng Fang Xuan-Yi Du Li-Lei Wang Prof. Dr. Xin-Yuan Liu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(39):17074-17080
We describe a photoinduced copper-catalyzed asymmetric radical decarboxylative alkynylation of bench-stable N-hydroxyphthalimide(NHP)-type esters of racemic alkyl carboxylic acids with terminal alkynes, which provides a flexible platform for the construction of chiral C(sp3)−C(sp) bonds. Critical to the success of this process are not only the use of the copper catalyst as a dual photo- and cross-coupling catalyst but also tuning of the NHP-type esters to inhibit the facile homodimerization of the alkyl radical and terminal alkyne, respectively. Owing to the use of stable and easily available NHP-type esters, the reaction features a broader substrate scope compared with reactions using the alkyl halide counterparts, covering (hetero)benzyl-, allyl-, and aminocarbonyl-substituted carboxylic acid derivatives, and (hetero)aryl and alkyl as well as silyl alkynes, thus providing a vital complementary approach to the previously reported method. 相似文献
11.
J. Cymerman Craig M. D. Bergenthal I. Fleming J. Harley-Mason 《Angewandte Chemie (International ed. in English)》1969,8(6):429-437
Eliminations leading from enol sulfonates, enol phosphates, and enol phosphonium salts to alkynes are reviewed. Olefin eliminations are usually the rate-determining step in the formation of the triple bond. Enol esters may also play a role in the biosynthesis of alkynes. 相似文献
12.
Mlodie Birepinte Pier Alexandre Champagne Jean-Franois Paquin 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2022,134(1):e202112575
A photoinitiated anti-hydropentafluorosulfanylation of terminal alkynes using SF5Cl and (TMS)3SiH as the hydrogen atom donor is reported. This transformation generates selectively (Z)-(1-alken-1-yl)pentafluoro-λ6-sulfanes (Z:E : >85:15), thus allowing the preparation of this previously unknown geometrical isomer. DFT calculations highlight that the selectivity is due to the intrinsic preference of SF5-substituted vinylic radicals to adopt a cis geometry, and to increased steric contacts during the transition structures leading to the minor (E)-products. 相似文献
13.
14.
A one‐pot synthesis of functionalized thiopyran derivatives via a Cu‐catalyzed multicomponent reaction of sulfonyl azides, arylacetylenes and dipotassium 2,2‐dicyanoethylene‐1,1‐dithiolate, generated from malononitrile and CS2, has been developed. When alkylacetylenes were used as the terminal alkynes, N‐(alkanethioyl)‐N‐(2,2‐dicyanoethanethioyl)methanesulfonamides were obtained in good yields. 相似文献
15.
Hai‐Dong Xia Zhong‐Liang Li Qiang‐Shuai Gu Xiao‐Yang Dong Jia‐Heng Fang Xuan‐Yi Du Li‐Lei Wang Xin‐Yuan Liu 《Angewandte Chemie (International ed. in English)》2020,59(39):16926-16932
We describe a photoinduced copper‐catalyzed asymmetric radical decarboxylative alkynylation of bench‐stable N‐hydroxyphthalimide(NHP)‐type esters of racemic alkyl carboxylic acids with terminal alkynes, which provides a flexible platform for the construction of chiral C(sp3)?C(sp) bonds. Critical to the success of this process are not only the use of the copper catalyst as a dual photo‐ and cross‐coupling catalyst but also tuning of the NHP‐type esters to inhibit the facile homodimerization of the alkyl radical and terminal alkyne, respectively. Owing to the use of stable and easily available NHP‐type esters, the reaction features a broader substrate scope compared with reactions using the alkyl halide counterparts, covering (hetero)benzyl‐, allyl‐, and aminocarbonyl‐substituted carboxylic acid derivatives, and (hetero)aryl and alkyl as well as silyl alkynes, thus providing a vital complementary approach to the previously reported method. 相似文献
16.
Dr. Pin Gao Dr. Xian‐Rong Song Prof. Dr. Xue‐Yuan Liu Prof. Dr. Yong‐Min Liang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(21):7648-7661
In the last few years, the development of versatile methodologies to incorporate trifluoromethyl groups into organic molecules has attracted significant attention in synthetic chemistry. This review gives an overview over the development on the trifluoromethylation of alkynes, which have not been solely discussed before. Formation of diverse C(sp, sp2, sp3)?CF3 bonds are all covered in this review. 相似文献
17.
Ali Sharifi Mojtaba Mirzaei M. Reza Naimi-Jamal 《Monatshefte für Chemie / Chemical Monthly》2006,137(2):213-217
Summary. A variety of 1,3-diyne compounds are prepared in a solvent-free reaction on KF/alumina in the presence of catalytic amounts
of Cu(OAc)2·H2O with up to 96% yields at room temperature. 相似文献
18.
A sulfonyl-radical-induced addition-cyclization reaction of 1,6-dienes with p-toluenesulfonyl cyanide giving functionalized cyclopentane systems is described. 相似文献
19.
Shashank P. Sancheti Yukta Singh Manoj V. Mane Nitin T. Patil 《Angewandte Chemie (International ed. in English)》2023,62(42):e202310493
Herein, we report the first gold-catalyzed 1,2-dicarbofunctionalization of alkynes using organohalides as non-prefunctionalized coupling partners. The mechanism of the reaction involves an oxidative addition/π-activation mechanism in contrast to the migratory insertion/cis-trans isomerization pathway that is predominantly observed with other transition metals yielding products with anti-selectivity. Mechanistic insights include several control experiments, NMR studies, HR-MSMS analyses, and DFT calculations that strongly support the proposed mechanism. 相似文献
20.
Masaki Shimoi Takashi Watanabe Prof. Katsuhiro Maeda Prof. Dennis P. Curran Dr. Tsuyoshi Taniguchi 《Angewandte Chemie (International ed. in English)》2018,57(30):9485-9490
Hydroboration of internal alkynes with N‐heterocyclic carbene boranes (NHC‐boranes) occurs to provide stable NHC (E)‐alkenylboranes upon thermolysis in the presence of di‐tert‐butyl peroxide. The E isomer results from an unusual trans‐hydroboration, and the E/Z selectivity is typically high (90:10 or greater). Evidence suggests that this hydroboration occurs by a radical‐chain reaction involving addition of an NHC‐boryl radical to an alkyne to give a β‐NHC‐borylalkenyl radical. Ensuing hydrogen abstraction from the starting NHC‐borane provides the product and returns the starting NHC‐boryl radical. Experiments suggest that the observed trans‐selectivity results from kinetic control in the hydrogen‐transfer reaction. 相似文献