- Au-Catalyzed Intermolecular [2+2] Cycloadditions between Chloroalkynes and Unactivated Alkenes
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The [2+2] cycloaddition is a versatile strategy for the synthesis of strained cyclobutenes of high synthetic value. In this study, two efficient intermolecular [2+2] cycloadditions between two different types of chloroalkynes and unactivated alkene are realized with gold catalysis. Of significance is that the reaction works with challenging monosubstituted unactivated alkenes, which is unprecedented in gold catalysis and scarcely documented in other metal-catalyzed/promoted reactions; moreover, the reaction exhibits excellent regioselectivities, which are much better than those reported in literature. With 1,2-disubstituted unactivated alkenes, the reaction is largely stereospecific. The cyclobutene products can be prepared in nearly gram scale and readily undergo further reactions including various cross-coupling reactions using the C(sp2)-Cl and/or C(sp2)-SPh bond, which in turn substantially broaden the scope of accessible cyclobutenes and enhance the synthetic utility of this bimolecular reaction.
- Bai, Yu-Bin,Luo, Zaigang,Wang, Yuguang,Gao, Jin-Ming,Zhang, Liming
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supporting information
p. 5860 - 5865
(2018/05/14)
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- A New Approach to the Synthesis of Symmetrical Bis(organylchalcogeno)acetylenes: Scope and Limitations
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A new general method to prepare bis(organylchalcogeno)acetylenes R-Y-CC-Y-R (Y = S, Se, Te) by dehydrochlorination of the corresponding 1,2-bis(organylchalcogeno)chloroethylenes R-Y-CH=CCl-Y-R with tert-BuOK/tert-BuOH and/or KOH/DMSO is developed.Dechlorination of 1,2-bis(organylchalcogeno)-1,2-dichloroethylenes R-Y-CCl=CCl-Y-R (Y = S, Se, Te) with BuLi in ether or THF is effective only for sulfur derivatives.With Y = Se and alkyl substituents, substitution of the chlorine atom by a butyl group takes place giving rise to 5,6-bis(alkylseleno)dec-5-ene .With aryl substituents, an attack of the ArSe-group by the Bu-radical is observed leading to an aryl butyl selenide.In the case of the tellurium compound Ph-Te-CCl=CCl-Te-Ph, there is a competition between dechlorination to give Ph-Te-CC-Te-Ph, and substitution to produce the phenyl butyl telluride. - Keywords: bis(organylchalcogeno)acetylene; 1,2-bis(organylchalcogeno)chloroethylene; 1,2-bis(organochalcogeno)-1,2-dichloroethylene.
- Martynov, Alexander V.,Guillanton, Georges Le
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p. 823 - 831
(2007/10/03)
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- FREE-RADICAL REACTION OF DIARYL DISULFIDES WITH TRI- AND TETRACHLOROETHYLENES
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The free-radical reaction of diaryl disulfides ArSSAr with CHCl=CCl2 leads to aryl β,β- and α,β-dichlorovinyl sulfides, trichlorovinyl sulfides, and the trichloroethylene dimer 1,1,3,3,4,4,-hexachloro-1-butene.In the reaction of diaryl disulfides with tetrachloroethylene aryl trichlorovinyl sulfides and hexachloro-1,3-butadiene are formed.A reaction mechanism involving reaction of the vinyl radicals CCl2=C.Cl, CCl2=C.H, adn CHCl-C.Cl with the arylthiyl radical is proposed.
- Martynov, A. V.,Mirskova, A. N.,Voronkov, M. G.
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- FREE-RADICAL REACTION OF ARENETHIOLS WITH TETRACHLOROETHYLENE
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The reaction of arenethiols ArSH (Ar = p-Tol, Ph, 4-ClC6H4) with tetrachloroethylene, initiated by UV irradiation or benzoyl peroxide, leads to the formation of mixtures of unsaturated and saturated products, i.e., aryl α,β-dichlorovinyl and β,β-dichlorovinyl sulfides, trichlorovinyl sulfides, 1,1,2,2-tetrachloroethyl and 1,2,2,2-tetrachloroethyl sulfides, diaryl disulfides, and isomeric diarylthiodichloroethenes.During discussion of the reaction mechanism, which involves reaction of the ArS radical with the tetrachloroethylene, evidence is given in favor of an α,β-chlorotropic rearrangement of the intermediate radical ArSCCl2CCl2 to the radical ArSCClCCl3.After the appropriate treatment it is possible to isolate the aryl trichlorovinyl sulfides in a mixture with small amount of aryl α,β-dichlorovinyl and aryl β,β-dichlorovinyl sulfides.
- Martynov, A. V.,Mirskova, A. N.,Voronkov, M. G.
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p. 1635 - 1640
(2007/10/02)
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