Rhenium-Catalyzed Insertion of Nonpolar and Polar Unsaturated Molecules into an Olefinic C−H Bond

Abstract

Treatment of olefins bearing a directing group with alpha,beta-unsaturated carbonyl compounds, alkynes, or aldehydes in the presence of a catalytic amount of a rhenium complex, [ReBr(CO)(3)(thf)](2) gave gamma,delta-unsaturated carbonyl compounds, dienes, and allyl silyl ethers, respectively. This reaction proceeds via C-H bond activation, insertion of unsaturated molecules into the formed rhenium-carbon bond, and then reductive elimination (or transmetalation in the case of aldehydes).

Selective Alkenylation and Hydroalkenylation of Enol Phosphates through Direct CH Functionalization

“…[15] In fact, compared to the impressive advancements in the catalytic addition of aryl C(sp 2 )-M intermediates, generated in situ upon C À Ha ctivation, to polarized C À X (X = N, O, C) unsaturated bonds, [16] chelation-assisted vinyl CÀHb ond addition to CÀXb onds has received much less attention and is still ac hallenging subject. [17] To our satisfac- . .…”

“…Gratifyingly,aseries of multisubstituted 1,3-dienes (5a-e) could be obtained with 34-83 %y ields and high selectivity under mild reaction conditions (Table 3). [17] To our satisfac- . [13] In view of that fact that enones are well-established as superior electrophiles in catalytic conjugate addition reactions, [14] we speculated that the direct addition of a Z-selective vinyl CÀHb ond to enone could be realized by using an appropriate directing group,which will open new horizons for the generation of g,d-unsaturated carbonyls in acomplementary stereoselective manner by other mechanistically different strategies.…”

Transition-Metal-Catalyzed C–H Bond Addition to Carbonyls, Imines, and Related Polarized π Bonds

“…16 Although the [MnBr(CO) 5 ] catalyst employed for arene C–H functionalization was found to be catalytically active toward the transformation, 15 the third-row congener [ReBr(CO) 3 (thf)] 2 proved to be an optimal catalyst. Electron-rich and poor aromatic, heteroaromatic, and alkyl aldehydes all coupled efficiently.…”

Development of Novel and Highly Efficient Methods to Construct Carbon–Carbon Bonds Using Group 7 Transition-Metal Catalysts

“…For example, Grignard-type reaction proceeded using aldehydes as substrates (Scheme 21). 30 A similar insertion of aldehydes also occurred in the presence of a manganese catalyst, [MnBr(CO) 5 ], however the yields were lower than those of rhenium-catalyzed reactions.…”