Copper‐Catalyzed Cross‐Coupling of Alkyl and Aryl Grignard Reagents with Alkynyl Halides

Abstract

1 - ArticleGood old copper! A new general procedure to couple aliphatic and aromatic Grignard reagents with alkynyl halides under copper catalysis is described (see scheme; NMP=N-methylpyrrolidinone). The reaction is chemoselective and allows preparation of a vast array of simple and functionalized internal alkynes in high yields

Copper‐Catalyzed Cross‐Coupling Reaction of Organoboron Compounds with Primary Alkyl Halides and Pseudohalides

“…[3] To solve this problem, several research groups have developed copper-catalyzed alkylation reactions of Grignard reagents. [3][4][5] It was found that these catalytic reactions are much easier to carry out and considerably less expensive. Additives, such as 1-methyl-2-pyrrolidinone and 1-phenylpropyne, were originally used to promote the alkylation reactions, [4] and the slow addition of the Grignard reagent was found to provide similar results in a recent study.…”

“…[3][4][5] It was found that these catalytic reactions are much easier to carry out and considerably less expensive. Additives, such as 1-methyl-2-pyrrolidinone and 1-phenylpropyne, were originally used to promote the alkylation reactions, [4] and the slow addition of the Grignard reagent was found to provide similar results in a recent study. [5] Although primary alkyl halides (as well as mesylates and tosylates) are mostly used in these catalytic alkylation reactions, some studies have indicated that secondary and even tertiary alkyl halides may also be possible coupling partners.…”

“…This feature compares favorably with previous examples of the copper-catalyzed coupling of primary alkyl halides with Grignard reagents, in which nearly all reported alkyl groups were hydrocarbons. [3][4][5] Furthermore, for the synthesis of 5 ab, we changed the catalyst from CuI to CuOtBu generated in situ through the equimolar reaction of anhydrous CuI with LiOtBu in THF at room temperature under nitrogen. The yield with CuOtBu was 90 %, which is slightly higher than that observed with CuI (86 %).…”

Rhenabenzenes and Unexpected Coupling Products from the Reactions of Rhenacyclobutadienes with Ethoxyethyne

“…The spectroscopic data are in accordance with the published data. 20 General Procedure for the Preparation of Rhenacyclobutadiene Complexes. To a solution of Na[Re(CO) 5 ] (0.500 g, 1.43 mmol) in THF (20 mL) was slowly added one equivalent of methyl 3-(naphthalen-1-yl)propiolate (0.30 g, 1.43 mmol) in THF (20 mL) at RT.…”

“…8 (s,OCH 3 ),124.0,126.6,126.8,127.5,127.6,127.7,129.9,130.1,135.0,148.2 (all s,C of Np), 156.9 (s, C(CO 2 Me)), 160.2 (s, CO 2 Me), 192.0 (s, trans-Re(CO)), 193.1 (s, Re(CO)), 194.8 (s, Re(CO)), 230.5 (s, ReC(Np)), 249.6 (s, ReC(OMe)). Elemental analysis (%) calcd for C 20 124.4, 126.6, 125.4, 125.5, 125.6, 127.7, 127.9, 132.8, 146.0 (all s, C of Np), 155.0 (s, C(CO 2 Me)), 158.1 (s, CO 2 Me), 190.0 (s, transRe(CO)), 190.9 (s, Re(CO)), 192.6 (s, Re(CO)), 227.5 (s, ReC(Np)), 244.8 (s, ReC(O n Pr)). Elemental analysis (%) calcd for C 22 General Procedure for the Reactions of Rhenacyclobutadiene Complexes with HCCOEt.…”