排序方式: 共有39条查询结果,搜索用时 15 毫秒
1.
G.K. Surya Prakash Jinbo Hu Ying Wang George A. Olah 《Journal of fluorine chemistry》2005,126(4):527-532
A fluoride-induced nucleophilic (phenylthio)difluoromethylation method using TMS-CF2SPh has been achieved. This new methodology efficiently transfers “PhSCF2” group into both enolizable and non-enolizable aldehydes and ketones to give corresponding (phenylthio)difluoromethylated alcohols in good to excellent yields. Diphenyldisulfide can also be (phenylthio)difluoromethylated into PhSCF2SPh in high yield. The reaction with methyl benzoate, however, gives only low yield of (phenylthio)difluoromethyl phenyl ketone. The above-obtained PhSCF2-containing alcohols can be further transformed into difluoromethyl alcohols using an oxidation-desulfonylation procedure. This new type of nucleophilic (phenylthio)difluoromethylation methodology may have other potential applications in the medicinal and agrochemical fields. 相似文献
2.
Xin Yuan Yu-Sheng Cui Xin-Peng Zhang Long-Zhou Qin Qi Sun Xiu Duan Lin Chen Guigen Li Jiang-Kai Qiu Prof. Kai Guo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(21):6522-6528
Considering their unique roles in organic synthesis, and pharmaceutical and agrochemical applications, the development of fluoroalkylation, cyclization, and indole oxidative cleavage are important topics. Herein, an unprecedented electrochemical tri- and difluoromethylation/cyclization/indole oxidative cleavage process occurring in an undivided cell is presented. The protocol employs a readily prepared Langlois reagent as the fluoroalkyl source, affording a series of tri- or difluoromethylated 2-(2-acetylphenyl)isoquinoline-1,3-diones in good yields with excellent stereoselectivity. It is worth noting that this new methodology merges the fluoroalkylation/cyclization of N-substituted acrylamide alkenes with the oxidative cleavage of an indole C(2)=C(3) bond under external oxidant-free conditions. 相似文献
3.
Nucleophilic Difluoromethylation of Epoxides with PhSO(NTBS)CF2H by a Preorganization Strategy
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Dr. Xiao Shen Qinghe Liu Tao Luo Prof. Dr. Jinbo Hu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(22):6795-6800
Unlike the facile synthesis of β‐monofluoromethyl alcohols by nucleophilic monofluoromethylation of epoxides, the synthesis of β‐difluoromethyl alcohols by nucleophilic difluoromethylation of epoxides still remains a challenge. Herein, studies on tackling this problem with PhSO(NTBS)CF2H ( 2 ; TBS=tert‐butyldimethylsilyl) are reported. The preorganization of 2 and epoxides with BF3 ? Et2O was found to be crucial for the reaction. The reaction shows excellent regioselectivity and has a broad substrate scope. The facile transformation of the ring‐opened products to β‐difluoromethyl, γ‐difluoromethyl, and β‐difluoromethylenyl alcohols demonstrates the synthetic utility of the reaction. 相似文献
4.
Wai Chung Fu Timothy F. Jamison 《Angewandte Chemie (International ed. in English)》2020,59(33):13885-13890
The deuteriodifluoromethyl group (CF2D) represents a challenging functional group due to difficult deuterium incorporation and unavailability of precursor reagents. Herein, we report the use of chlorodifluoromethane (ClCF2H) gas in the continuous flow deuteriodifluoromethylation and gem‐difluoroalkenylation of aldehydes. Mechanistic studies revealed that the difluorinated oxaphosphetane (OPA) intermediate can proceed via alkaline hydrolysis in the presence of D2O to provide α‐deuteriodifluoromethylated benzyl alcohols or undergo a retro [2+2] cycloaddition under thermal conditions to provide the gem‐difluoroalkenylated product. 相似文献
5.
Palladium‐Initiated Radical Cascade Stereoselective Iodofluoroalkylation/Cycloisomerization of Ene‐vinylidenecyclopropanes
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Song Yang Dr. Qin Xu Prof. Dr. Min Shi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(30):10387-10392
A novel and convenient palladium‐initiated radical cascade stereoselective iodofluoroalkylation/cycloisomerization of ene‐vinylidenecyclopropanes with fluoroalkyl iodides has been developed. The reaction proceeds under mild reaction conditions with high atom economy and stereoselectivity, thereby allowing an efficient access to a variety of difluoromethylated or perfluoroalkylated pyrrolidines tethered with an alkyl iodide. Two plausible radical pathways for the transformation have been proposed on the basis of the results of control experiments and previous reports, which in one case it was thought that palladium(0) was an initiator rather than a catalyst. 相似文献
6.
Dr. Jun Liu Prof. Dr. Jinbo Hu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(37):11443-11454
The first highly efficient and stereoselective difluoromethylation of structurally diverse N‐tert‐butylsulfinyl ketimines has been achieved with an in situ generated PhSO2CF2? anion, which provides a powerful synthetic method for the preparation of a variety of structurally diverse homochiral α‐difluoromethyl tertiary carbinamines, including α‐difluoromethyl allylic amines and α‐difluoromethyl propargylamines. The stereocontrol mode of the present diastereoselective difluoromethylation of ketimines was found to be different from that of other known fluoroalkylations of N‐tert‐butylsulfinyl aldimines, which suggests that a cyclic six‐membered transition state may be involved in the reaction. 相似文献
7.
Dr. Pavel K. Mykhailiuk 《Angewandte Chemie (International ed. in English)》2015,54(22):6558-6561
A novel approach to agrochemically important difluoromethyl‐substituted pyrazoles has been developed based on the elusive reagent CF2HCHN2, which was synthesized (generated in situ) for the first time and employed in [3+2] cycloaddition reactions with alkynes. The reaction is extremely practical as it is a one‐pot process, does not require a catalyst or the isolation of the potentially toxic and explosive gaseous intermediate, and proceeds in a common solvent, namely chloroform, in air. The reaction is also scalable and allows for the preparation of the target pyrazoles on gram scale. 相似文献
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9.
Vlad Bacauanu Sébastien Cardinal Motoshi Yamauchi Masaru Kondo David F. Fernández Richard Remy Prof. Dr. David W. C. MacMillan 《Angewandte Chemie (International ed. in English)》2018,57(38):12543-12548
Herein, we report a convenient and broadly applicable strategy for the difluoromethylation of aryl bromides by metallaphotoredox catalysis. Bromodifluoromethane, a simple and commercially available alkyl halide, is harnessed as an effective source of difluoromethyl radical by silyl‐radical‐mediated halogen abstraction. The merger of this fluoroalkyl electrophile activation pathway with a dual nickel/photoredox catalytic platform enables the difluoromethylation of a diverse array of aryl and heteroaryl bromides under mild conditions. The utility of this procedure is showcased in the late‐stage functionalization of several drug analogues. 相似文献
10.
A simple and efficient protocol for difluoromethylation of isoflavones, flavonoids, and coumarins has been developed. The protocol uses readily available, non-ozone-depleting and easy handling BrCF2PO(OEt)2 as difluorocarbene precursor. The reaction underwent the formation of difluorocarbene under mild reaction conditions with relatively weak base therefore demonstrates high selectivity. Application of the reaction led to difluoromethylated biologically relevant molecules. 相似文献