共查询到20条相似文献,搜索用时 57 毫秒
1.
2.
Seung‐Mann Paek Dr. Nam‐Jung Kim Dongyun Shin Dr. Jae‐Kyung Jung Prof. Jong‐Wha Jung Dr. Dong‐Jo Chang Dr. Hyunyoung Moon Young‐Ger Suh Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(15):4623-4628
Highly concise asymmetric total syntheses of (+)‐tetrabenazine ( 1 ), a drug for the treatment of chorea associated with Huntington’s disease, and of (+)‐α‐dihydrotetrabenazine ( 2 ), an active metabolite of 1 , have been accomplished. Our synthetic route features a trans‐selective enol etherification, followed by an unprecedented cation‐dependent aza‐Claisen rearrangement to establish the carbon framework and two stereogenic centers of tetrabenazine. The syntheses consist of seven steps (34 % overall yield) for (+)‐ 2 and eight steps (22 % overall yield) for (+)‐ 1 . 相似文献
3.
New syntheses of 4‐alkoxy‐3‐methoxy‐5H‐benzocycloheptenes and 2‐alkoxy‐3‐methoxy‐5H‐benzocycloheptenes were studied. Based on Claisen rearrangement, O‐alkylation, nucleophilic addition of allyl magnesium bromide, ring‐closing metathesis, and dehydration, a series of new 4‐alkoxy‐3‐methoxy‐5H‐benzocycloheptenes and 2‐alkoxy‐3‐methoxy‐5H‐benzocycloheptenes were respectively synthesized from isovanillin in good overall yields. 相似文献
4.
5.
Ren Hommelsheim Yujing Guo Zhen Yang Claire Empel Rene M. Koenigs 《Angewandte Chemie (International ed. in English)》2019,58(4):1203-1207
Carbenes are very important reactive intermediates to access a variety of complex molecules and are applied widely in organic synthesis and drug discovery. Typically, their chemistry is accessed by the use of transition metal catalysts. Herein, we describe the application of low‐energy blue light for the photochemical generation of carbenes from donor–acceptor diazoalkanes. This catalyst‐free and operationally simple approach enables highly efficient cyclopropenation reactions with alkynes and the rearrangement of sulfides under mild reaction conditions, which can be utilized for both batch and continuous‐flow processes. 相似文献
6.
7.
Rama Rao Tata Carissa S. Hampton Erich F. Altenhofer Michael Topinka Weijiang Ying Xuefeng Gao Prof. Dr. Michael Harmata 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(42):13547-13550
Herein, attempted oxidation of selected allenols with PCC affording α′‐hydroxydienones rather than simple oxidation products is described. The formation of the products observed is rationalized via a series of sigmatropic shifts, followed by hydrolysis. 相似文献
8.
A modified synthetic route of [3,3′‐di‐sec‐butyl‐4′‐(2‐dimethylaminoethoxy)biphenyl‐4‐yloxy]acetic acid ( 1 ) with high total yield of 44% from biphenyl‐4,4′‐diol ( 2 ) is described. 相似文献
9.
Gold‐Catalyzed Cascade Cyclization of 2‐Alkynyl‐N‐Propargylanilines by Rearrangement of a Propargyl Group 下载免费PDF全文
Yusuke Tokimizu Dr. Shinya Oishi Prof. Dr. Nobutaka Fujii Prof. Dr. Hiroaki Ohno 《Angewandte Chemie (International ed. in English)》2015,54(27):7862-7866
Gold catalysis enables direct construction of tetracyclic fused indolines through the migration of a propargyl substituent from an aniline nitrogen atom to the C3‐position of an indole from 2‐alkynyl‐N‐propargylanilines. This reaction provides rapid access to fused three‐dimensional indolines in a single operation with the formation of four bonds and three rings. 相似文献
10.
Copper‐Catalyzed Aerobic Oxidations of 3‐N‐Hydoxyaminoprop‐1‐ynes to Form 3‐Substituted 3‐Amino‐2‐en‐1‐ones: Oxidative Mannich Reactions with a Skeletal Rearrangement 下载免费PDF全文
Rahul Kisan Kawade Chang‐Chin Tseng Prof. Dr. Rai‐Shung Liu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(43):13927-13931
Cu‐catalyzed aerobic oxidations of readily available 3‐N‐hydroxyaminopro‐1‐ynes with water, alcohols, or thiols to form diverse 3‐substituted 3‐amino‐2‐en‐1‐ones are described. The utility of this catalysis is manifested by a wide scope of applicable N‐hydroxyl propargylamines and nucleophiles, thus enabling the design of one‐pot cascade or two‐step sequential reactions. Besides synthetic significances, such oxidative Mannich reactions are mechanistically interesting because structurally reorganized products were obtained. Our mechanistic studies reveal that the aerobic oxidations involve initial formation of nitrone intermediates, followed by the attack of nucleophiles. Herein, water and MeOH implement the conversion of nitrone intermediates to reaction products in two distinct pathways. 相似文献
11.
Zhitong Zheng Huangfei Tu Prof. Dr. Liming Zhang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(9):2445-2448
A two‐step, one‐pot synthesis of fused pyrroles is realized by firstly condensing an N‐alkynylhydroxammonium salt with a readily enolizable ketone under mild basic conditions and then subjecting the reaction mixture to a gold catalyst, which triggers a cascade reaction involving a facile initial [3.3]‐sigmatropic rearrangement of the gold‐catalysis product, that is, an N,O‐dialkenylhydroxamine. The reaction provides a facile access to polycyclic pyrroles in moderate to good yields. 相似文献
12.
13.
14.
Intramolecular Metal‐Free Oxidative Aryl–Aryl Coupling: An Unusual Hypervalent‐Iodine‐Mediated Rearrangement of 2‐Substituted N‐Phenylbenzamides 下载免费PDF全文
Siyun Shang Dr. Daisy Zhang‐Negrerie Prof. Dr. Yunfei Du Prof. Dr. Kang Zhao 《Angewandte Chemie (International ed. in English)》2014,53(24):6216-6219
Hypervalent‐iodine‐mediated oxidative coupling of the two aryl groups in either 2‐acylamino‐N‐phenyl‐benzamides or 2‐hydroxy‐N‐phenylbenzamides, with concomitant insertion of the ortho‐substituted N or O atom into the tether, has been described for the first time. This unusual metal‐free rearrangement reaction involves an oxidative C(sp2)? C(sp2) aryl–aryl bond formation, cleavage of a C(sp2)? C(O) bond, and a lactamization/lactonization. Furthermore, unsymmetrical diaryl compounds can be easily obtained by removing the tether within the cyclized product. 相似文献
15.
Photo‐irradiation of 2‐(5‐methylthiophen‐2‐yl)‐3‐[(naphthalen‐2‐yl)methoxy]‐4H‐chromen‐4‐ones yielded the fascinating angular tetracyclic products via cyclization involving both 2‐thienyl ring and naphthylmethoxy group via 1,4‐biradical generated in the Norrish type‐II process. The stereochemical dispositions of the products were determined by MM2 energy minimized programme and spectroscopic analysis. 相似文献
16.
Competitive Gold‐Promoted Meyer–Schuster and oxy‐Cope Rearrangements of 3‐Acyloxy‐1,5‐enynes: Selective Catalysis for the Synthesis of (+)‐(S)‐γ‐Ionone and (−)‐(2S,6 R)‐cis‐γ‐Irone 下载免费PDF全文
Dr. Serena Bugoni Dr. Valentina Merlini Dr. Alessio Porta Dr. Sylvain Gaillard Prof. Giuseppe Zanoni Prof. Dr. Steven P. Nolan Prof. Giovanni Vidari 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(40):14068-14074
We report a simple, highly stereoselective synthesis of (+)‐(S)‐γ‐ionone and (‐)‐(2S,6R)‐cis‐γ‐irone, two characteristic and precious odorants; the latter compound is a constituent of the essential oil obtained from iris rhizomes. Of general interest in this approach are the photoisomerization of an endo trisubstituted cyclohexene double bond to an exo vinyl group and the installation of the enone side chain through a [(NHC)AuI]‐catalyzed Meyer–Schuster‐like rearrangement. This required a careful investigation of the mechanism of the gold‐catalyzed reaction and a judicious selection of reaction conditions. In fact, it was found that the Meyer–Schuster reaction may compete with the oxy‐Cope rearrangement. Gold‐based catalytic systems can promote either reaction selectively. In the present system, the mononuclear gold complex [Au(IPr)Cl], in combination with the silver salt AgSbF6 in 100:1 butan‐2‐one/H2O, proved to efficiently promote the Meyer–Schuster rearrangement of propargylic benzoates, whereas the digold catalyst [{Au(IPr)}2(μ‐OH)][BF4] in anhydrous dichloromethane selectively promoted the oxy‐Cope rearrangement of propargylic alcohols. 相似文献
17.
GOLOLOBOV Yuri G. 《中国化学》2005,23(8):1103-1105
A new type of intramolecular electrophilic rearrangements involving the shift of alkoxycarbonyl or acetyl groups from a carbon atom to an N-anionic center is presented. 相似文献
18.
José Gustavo Ávila‐Zárraga Adrián Vázquez‐Sánchez Luis Ángel Maldonado 《Helvetica chimica acta》2013,96(7):1331-1338
The results of an aromatic Cope rearrangement of a trans‐1‐aryl‐2‐ethenylcyclobutanecarbonitrile are reported (Scheme). The use of this rearrangement for the construction of the fused benzocyclooctene ring system and a preliminary study of the electronic requirements to favor such a transformation are also described. 相似文献
19.
Vladimír Bariak Dr. Andrea Malastová Dr. Ambroz Almássy Prof. Radovan Šebesta 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(38):13445-13453
An intramolecular Li–Si exchange was observed on various lithiated ferrocenylbenzyl silyl ethers. The thermodynamically more stable C‐silylated isomers were isolated in good yields and fully characterized. The reaction mechanism of the [1,4] retro‐Brook rearrangement was investigated by DFT calculations. Two distinct reaction routes were proposed and a possible stabilization effect of the ferrocenyl fragment on the C‐silylated isomers was described. The diastereoselective rearrangement of the trimethylsilyl group to the ortho position of the ferrocenyl cyclopentadienyl ring was also accomplished and the absolute configuration of the product was determined. 相似文献