Cobalt‐Catalyzed Diastereo‐ and Enantioselective Hydroalkenylation of Cyclopropenes with Alkenylboronic Acids

Abstract

Catalytic diastereo‐ and enantioselective hydroalkenylation of 3,3‐disubstituted cyclopropenes with readily accessible alkenylboronic acids, promoted by a chiral phosphine/Co complex, is presented. Such a process constitutes the unprecedented and direct introduction of a wide range of alkenyl groups onto the cyclopropane motif to afford multisubstituted cyclopropanes in up to 95 % yield with greater than 95:5 d.r. and 99:1 e.r. Functionalization of the products delivered enantioenriched cyclopropanes that are otherwise difficult to access.

Migratory Hydrogenation of Terminal Alkynes by Base/Cobalt Relay Catalysis

“…In contrast, this migratory hydrogenation strategy enabled a straightforward synthesis of 3 i from the terminal alkyne 1 i with 91 % yield (Scheme ). As illustrated in Scheme , 3 i could be readily transformed into a range of other valuable compounds, including the diol 5 , epoxide 6 , cyclopropyl product 7 , furan derivatives ( 8 and 10 ), and organo mercury compound 9 by applying various known procedures.…”

“…Communications readily transformed into a range of other valuable compounds, including the diol 5, [17] epoxide 6, [18] cyclopropyl product 7, [9d] furan derivatives (8 [19] and 10 [9d] ), and organo mercury compound 9 [20] by applying various known procedures.…”

Synthetic Applications of Cyclopropene and Cyclopropenone: Recent Progress and Developments

“…Marek's hydroarylation [17] using Rh-catalyst, Meng's team [18] disclosed a cheaper phosphine ligated cobalt-catalyzed enantioselective hydroalkenylation of cyclopropenes 21 with a wide range of alkenyl boronic acids 28 {(E)-1,2-disubstituted alkenyl boronic acids bearing electron-deficient, electron-rich, sterically congested aryls, heteroaryl, alkenyl and alkyl groups}. Cyclopropenes 21 bearing adamantyl and t butyl methoxy dimethylsilyl groups give a poor yield of the product 30.…”

Dimeric Manganese‐Catalyzed Hydroarylation and Hydroalkenylation of Unsaturated Amides

“…A Compared to arylboronic acids, alkenyl boronic acids have rarely been studied in manganese catalysis. [36][37][38] The major challenge in the reaction stems from the facile protodemetalation side reactions that occur as a result of the high reactivity of metal alkenyl compounds. Based on our successful hydroarylation of unsaturated secondary amides, giving for example 3 p, (Scheme 2), we found by replacement of CsF with K 2 CO 3 in the hydroarylation reaction, that the challenging alkenyl boronic acids are competent coupling partners with Mn 2 (CO) 8 Br 2 as the catalyst.…”