2-Furylzinc chloride

Negishi coupling of 2-furylzinc chloride with vinyl telluride provided 2-substituted furan with (Z)-double bond in a stereoselective manner, which was used in the total synthesis of l-(Z)-atractylodinol, a biologically active natural product as depicted in the following scheme <06TL8183>... 

Treating 2-furyltithium (derived from deprotonation of furan with n-BuLi) with ZnCh gave 2-furylzinc chloride, which then was coupled with 1,3-dibromobenzene to furnish bis-furylbenzene 12 [20, 21]. In addition, 2-furylzinc chloride was coupled with 4-iodobenzoic acid to give adduct 13. The Negishi reaction conditions were compatible with the carboxylic acid [22],... 

Both vinyl- and aryl triflates have been cross-coupled with 2-furylzinc chloride [26-28]. Since vinyl triflates are easily obtained from the corresponding ketones, they are useful substrates in Pd-catalyzed reactions. In the following example, a Negishi coupling of 2-furylzinc chloride and indol-5-yl triflate (22) provided an expeditious entry to 2-(5 -indolyl)furan (23). Protection of the NH in the indole ring was not required. A similar reaction was successful with pyridyl- and quinolinyl triflates. 

Unlike normal all-carbon aryl halides, regioselective Negishi coupling reaction of 2,3-dibromofuran 27 with 2-furylzinc chloride was achieved at C(2) to afford bisfuran 28 [35]. 

Fischer indole synthesis, 157 fluorinated phosphine, 136 fuostifoline, 276 furo[2,3- ]pyridine, 281 furopyrimidine, 281, 393 furo[2,3-c]quinoline, 274 furylaniline, 272 furylboronic acid, 274 furylpyridine, 274 furylstannane, 277-9 2-furylzinc chloride, 271-4... 

Similarly, Negishi cross-coupling of 2-furylzinc chloride with 2,5-dibromothiophene in the presence of PdCl2(dppb) proceeded in moderate yield (45%) to give the monosubstituted product (dppb = l,4-bis(diphenylphosphino)butane). 

Fiuylzinc halides also undergo coupling with vinyl and aryl tellurides in a variation of the Negishi reaction. In one example, Z-vinylic telluride 35 reacts with 2-furylzinc chloride to furnish 2-vinylfuran 36 in 75% yield [47]. 

Triflates react similarly. The triflate of pyridin-3-ol has been coupled with 2-furylzinc chloride and Pd-catalysis to yield 3-(2-furyl)pyridine (288) (90SL47). 

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