- Direct dichlorovinylation of nitriles with trichloroethylene under phase-transfer catalysis conditions
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Reaction of trichloroethylene with nitriles 1a-k, carried out in the presence of 50% aqueous sodium hydroxide and tetrabutylammonium hydrogen sulfate as a phase-transfer catalyst, in diethyl ether at 5-10°C affords dichlorovinyl derivatives 2a-k in good yields. Deprotection of the latent carbonyl group in aminonitrile 1f results in the formation of dichlorovinyl ketone 5.
- Jończyk, Andrzej,Gierczak, Agnieszka H.
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- E - Z isomerization in Suzuki cross-couplings of haloenones: Ligand effects and evidence for a separate catalytic cycle
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Suzuki cross-coupling of haloalkenes is generally assumed to occur with retention of the alkene stereochemistry. While studying Suzuki cross-couplings on E-1,2-dichlorovinyl phenyl ketone, we were surprised to observe extensive isomerization. More surprisingly, the ligand employed strongly influenced the degree of isomerization: DPEphos and Xantphos led to 96% isomerized cross-coupled product whereas reactions in the absence of a phosphine ligand, or reactions employing t-BuXantphos, gave 94% retention of stereochemistry. While E-Z isomerization in Pd-catalyzed vinylic couplings has previously been attributed to events within the cross-coupling catalytic cycle, we present experimental and computational evidence for a separate Pd-catalyzed isomerization process in these reactions.
- Chehal, Navneet K.,Budzelaar, Peter H. M.,Hultin, Philip G.
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p. 1134 - 1143
(2018/02/22)
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