Iron-Catalyzed Negishi Coupling Toward an Effective Olefin Synthesis

Abstract

A selective iron-catalyzed cross-coupling of alkyl halides with alkenylzinc reagents is described. Primary and secondary alkyl chlorides, bromides, and iodides take part in the reaction to give the corresponding olefins in good to excellent yields in a stereospecific manner. High functional group compatibility is also demonstrated by using combinations of substrates possessing rather reactive substituents.

Decarboxylative alkenylation

“…29 Although Negishi, Kumada-Corriu-Tamao, and Suzuki-Miyaura type reactions enable the cross-coupling of olefin-containing organometallic species with alkyl halides with precise control of olefin geometry, 30 the limited availability of the latter species diminishes the utility of such a disconnection. 31–38 …”

Iron‐Catalyzed Alkyl–Alkyl Suzuki–Miyaura Coupling

“…Interestingly, the reaction with MeMgBr gave methylation product 4 (73 %) rather than 3 (8 %, Table 1, entry 4). [13] Similarly, the reaction with tBuMgCl did not give 3 but gave 5 and 6 (19 % and 12 % yields, respectively, Table 1, entry 6). [12] The reaction of a magnesium borate prepared with TMSCH 2 MgBr did not give 3 but gave heptanenitrile 5 and hept-6-enenitrile 6 in 19 % and 49 % yields, respectively, thus suggesting the selective transfer of the TMSCH 2 group from the borate [nBu 3 (TMSCH 2 )B][MgCl] ( Table 1, entry 5).…”

“…[13] Similarly, the reaction with tBuMgCl did not give 3 but gave 5 and 6 (19 % and 12 % yields, respectively, Table 1, entry 6). [14] [Fe(acac) 2 ], Fe(OAc) 2 , FeCl 2 , and FeCl 3 showed rather low or comparable catalytic activities (Table 1, entries [11][12][13][14]. [9] We assumed that the reaction with the remaining tBuMgCl took place prior to the coupling reaction with the activated alkyl boron compound, leading to the production of 5 and 6.…”

Carbon–Carbon Bond Forming Reactions Mediated by Organozinc Reagents

“…FeCl 3 in combination with TMEDA, is a competent catalytic system for the coupling between aryl- [216] or alkenylzincs [217] and primary or secondary alkyl halides including chlorides, as illustrated in the preparation of 292 (Scheme 4.64). In the case of alkenylzincs, complete retention of configuration is observed.…”

“…To a THF solution of (trimethylsilyl)methylzinc iodide (2.41 ml, 0.83 M, 2.00 mmol) was added a THF solution of (2-methylprop-1-enyl)magnesium bromide (2.94 ml, 0.68 M, 2.00 mmol), TMEDA (523 mg, 0.67 ml, 4.50 mmol), chlorocycloheptane (134 mg, 1.00 mmol), and a THF solution of FeCl 3 (0.50 ml, 0.10 M, 0.050 mmol, 5 mol%) at 0 • C, and the mixture was stirred at this temperature for 30 min and at 30 • C for 18 h (Scheme 4.65) [217]. After cooling to 0 • C, aqueous NH 4 Cl (saturated, 1.0 ml) was added.…”