Bu3SnR

Bu3SnR denotes organotin compounds in which a tributyltin group (SnBu3) is bonded to an organic substituent R. In practice this is written as R–SnBu3 or Bu3Sn–R and refers to a tetravalent tin center bearing three n-butyl groups and one organic group. The R substituent can be aryl, vinyl, alkyl, or other carbon-based groups. These reagents are part of Stille-type cross-coupling chemistry and related transmetalation processes.

Preparation of Bu3SnR typically involves transmetalation of Bu3SnCl or other Bu3SnX reagents with a nucleophilic organometallic partner such as RMgX or RLi to form R–SnBu3 after workup. Alternative routes include direct synthesis from organolithium or Grignard reagents followed by quenching with a tin source. These compounds are commonly prepared and stored under inert conditions due to their air- and moisture-sensitivity.

Key applications center on Stille cross-coupling, where R–SnBu3 serves as the tin-based nucleophile. In the presence of a palladium catalyst and appropriate ligands, the R moiety is transferred from tin to an electrophilic partner such as an aryl or vinyl halide or pseudohalide, forming a new C–C bond (R–R') and generating Bu3SnX as a byproduct. R–SnBu3 reagents enable the construction of aryl–aryl, vinyl–aryl, and other complex architectures, and they can be employed in sequential or tandem coupling strategies.

Safety and handling notes: organotin compounds can be hazardous and are subject to strict disposal regulations due to toxicity concerns. Appropriate protective equipment and waste management protocols are required.

See also: organotin chemistry, Stille coupling, tributyltin hydride, transmetalation.