15325-54-9Relevant articles and documents
Highly chemo- and stereoselective Fe-catalyzed alkenylation of organomanganese reagents
Cahiez, Gerard,Marquais, Sophie
, p. 1773 - 1776 (1996)
Organomanganese chlorides react with alkenyl iodides, bromides and chlorides in the presence of 3% Fe(acac)3. The reaction takes place under very mild conditions (THF-NMP, rt, 1h) to afford the substituted olefin in excellent yields with a high stereo- and chemoselectivity. Thus an unprotected keto alkenyl chloride selectively gives the corresponding keto olefin. From a preparative point of view, this procedure is the first real alternative to the Pd- and Ni-cross coupling reaction used until now.
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Parham,W.E. et al.
, p. 2698 - 2700 (1962)
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A facile stereoselective synthesis of (E)-1,2-disubstituted vinylic selenides via hydromagnesiation of alkylarylacetylenes
Cai, Mingzhong,Xia, Jun,Hao, Wenyan
, p. 65 - 68 (2005)
Hydromagnesiation of alkylarylacetylenes 1 in diethyl ether gave (E)-α-arylvinyl Grignard reagents 2, which reacted with arylselenenyl bromides 3 in THF to afford stereoselectively (E)-1,2-disubstituted vinylic selenides 4 in good yields.
Selective hydroboration of equilibrating allylic azides
Liu, Ruzhang,Xu, Jun,Zhang, Yuanyuan
supporting information, p. 8913 - 8916 (2021/09/13)
The iridium(i)-catalyzed hydroboration of equilibrating allylic azides is reported to provide only the anti-Markovnikov product of alk-1-ene isomers in good yields and with good functional group tolerance.
An Amine-Assisted Ionic Monohydride Mechanism Enables Selective Alkyne cis-Semihydrogenation with Ethanol: From Elementary Steps to Catalysis
Huang, Zhidao,Wang, Yulei,Leng, Xuebing,Huang, Zheng
, p. 4824 - 4836 (2021/04/07)
The selective synthesis of Z-alkenes in alkyne semihydrogenation relies on the reactivity difference of the catalysts toward the starting materials and the products. Here we report Z-selective semihydrogenation of alkynes with ethanol via a coordination-induced ionic monohydride mechanism. The EtOH-coordination-driven Cl- dissociation in a pincer Ir(III) hydridochloride complex (NCP)IrHCl (1) forms a cationic monohydride, [(NCP)IrH(EtOH)]+Cl-, that reacts selectively with alkynes over the corresponding Z-alkenes, thereby overcoming competing thermodynamically dominant alkene Z-E isomerization and overreduction. The challenge for establishing a catalytic cycle, however, lies in the alcoholysis step; the reaction of the alkyne insertion product (NCP)IrCl(vinyl) with EtOH does occur, but very slowly. Surprisingly, the alcoholysis does not proceed via direct protonolysis of the Ir-C(vinyl) bond. Instead, mechanistic data are consistent with an anion-involved alcoholysis pathway involving ionization of (NCP)IrCl(vinyl) via EtOH-for-Cl substitution and reversible protonation of Cl- ion with an Ir(III)-bound EtOH, followed by β-H elimination of the ethoxy ligand and C(vinyl)-H reductive elimination. The use of an amine is key to the monohydride mechanism by promoting the alcoholysis. The 1-amine-EtOH catalytic system exhibits an unprecedented level of substrate scope, generality, and compatibility, as demonstrated by Z-selective reduction of all alkyne classes, including challenging enynes and complex polyfunctionalized molecules. Comparison with a cationic monohydride complex bearing a noncoordinating BArF- ion elucidates the beneficial role of the Cl- ion in controlling the stereoselectivity, and comparison between 1-amine-EtOH and 1-NaOtBu-EtOH underscores the fact that this base variable, albeit in catalytic amounts, leads to different mechanisms and consequently different stereoselectivity.
