Stannylation of Aryl Halides, Stille Cross‐Coupling, and One‐Pot, Two‐Step Stannylation/Stille Cross‐Coupling Reactions under Solvent‐Free Conditions

Abstract

Dedicated to the memory of academician N. S. Zefirov.Abstract: Solvent-free protocols for palladium-catalyzed stannylation of aryl halides, Stille cross-coupling, and one-pot, twostep stannylation/Stille cross-coupling (SSC) are reported for the first time. (Het)aryl halides bearing acceptor, donor, as well as sterically demanding substituents are stannylated and/or coupled in high yields. The reactions are catalyzed by conventional palladium(II) acetate/PCy 3 [Pd(OAc) 2 /PCy 3 ] under air, using avail-

Nickel-Catalyzed Decarbonylative Stannylation of Acyl Fluorides under Ligand-Free Conditions

“…To demonstrate the synthetic utility of the present method, one-pot reaction of a successive decarbonylative stannylation/Migita-Kosugi-Stille reaction of 1a was investigated (Scheme 2) [31]. To our delight, with the aid of the additional palladium catalyst into the reaction mixture, 71% yield of compound 4 was obtained.…”

“…Without nickel(II) chloride, no target product 3a was formed, and 5 was obtained quantitatively (entry 3). In some stannylation reactions, hexabutyldistannane ( 5 ) could also be used as a stannylating reagent [30,31]. Thus, the reaction of 1a (0.2 mmol) with 5 (0.24 mmol) was evaluated under identical reaction conditions.…”

“…After 24 h, the reaction mixture was cooled, the volatiles were evaporated under reduced pressure. The product was purified by flash chromatography on silica gel by elution with hexane, compound 4 was obtained in 71% yield (30 mg, 0.14 mmol) as white solid [31].…”

“…Tributyl ( o-tolyl)stannane ( 3c ) [31]. Yield: 63% (48.0 mg); colorless oil; 1 H NMR (400 MHz, CDCl 3 ) δ 0.90 (t, J = 7.2 Hz, 9H), 1.01–1.14 (m, J H-Sn = 50.4 Hz, 6H), 1.34 (sext, J = 7.2 Hz, 6H), 1.47–1.58 (m, 6H), 2.40 (s, 3H), 7.12–7.17 (m, 1H), 7.17–7.25 (m, 2H), 7.40 (d, J = 6.8 Hz, J H-Sn = 42.8 Hz, 1H).…”

“…Conventional synthetic methods of arylstannanes are the reactions of organometallic reagents such as arylzinc compounds with triorganotin halides [25,26,27]. Alternatively, catalytic cross-coupling reactions of aryl (pseudo)halides with tributyltin hydride [28], tributylstannyl methoxide [29], and hexaalkyldistannane [30,31] have been documented (Scheme 1a). Recent studies on arylstannanes synthesis utilizing air- and moisture-insensitive silylstannyl reagent, Bu 3 Sn-SiMe 3 , could prove that the C–O bond is also a powerful alternative to aryl halides (Scheme 1b) [32].…”