Herbort, James H. published the artcileCationic Co(I) Catalysts for Regiodivergent Hydroalkenylation of 1,6-Enynes: An Uncommon cis-α-C-H Activation Leads to Z-Selective Coupling of Acrylates, Safety of Sodium chloro(tosyl)amide trihydrate, the publication is ACS Catalysis (2021), 11(15), 9605-9617, database is CAplus and MEDLINE.
Two intermol. hydroalkenylation reactions of 1,6-enynes N(R)(CH2CH=CH2)CH2CCR1 (R = -N(Ts)-, -C(COOEt)2-, -O-, -N(Boc)-; R1 = 4-fluorophenyl, thiophen-3-yl, prop-1-en-2-yl, etc.) are presented which yield substituted 5-membered carbo- and -heterocycles I (R = -N(Ts)-, -C(COOEt)2-; R2 = H, Me; R3 = H, Me, n-Bu). This reactivity is enabled by a cationic bis-diphenylphosphinopropane (DPPP)CoI species which forms a cobaltacyclopentene intermediate by oxidative cyclization of the enyne. This key species interacts with alkenes in distinct fashion, depending on the identity of the coupling partner to give regiodivergent products I. Simple alkenes undergo insertion reactions to furnish 1,3-dienes whereby one of the alkenes is tetrasubstituted. The acerylates R4CH=C(R5)C(O)OR6 (R4 = H, Me, OMe; R5 = H, Me; R6 = Me, Bn, Cy, t-Bu) were employed as coupling partners, and the site of intermol. C-C formation shifts from the alkyne to the alkene motif of the enyne, yielding Z-substituted-acrylate derivatives II. Computational studies provide support for the exptl. observations and show that the turnover-limiting steps in both reactions are the interactions of the alkenes with the cobaltacyclopentene intermediate via either a 1,2-insertion in the case of ethylene, or an unexpected α-C-H activation in the case of most acrylates. Thus, the H syn to the ester is activated through the coordination of the acrylate carbonyl to the cobaltacycle intermediate, which explains the uncommon Z-selectivity and regiodivergence. Variable time normalization anal. (VTNA) of the kinetic data reveals a dependence upon the concentration of cobalt, acrylate, and activator. A KIE of 2.1 was observed with Me methacrylate in sep. flask experiments, indicating that C-H cleavage is the turnover-limiting step in the catalytic cycle. Lastly, a Hammett study of aryl-substituted enynes yields a ρ value of -0.4, indicating that more electron-rich substituents accelerate the rate of the reaction.
ACS Catalysis published new progress about 7080-50-4. 7080-50-4 belongs to chlorides-buliding-blocks, auxiliary class Halogenation Reagent,Inhibitor, name is Sodium chloro(tosyl)amide trihydrate, and the molecular formula is C7H13ClNNaO5S, Safety of Sodium chloro(tosyl)amide trihydrate.
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