alkylstannane

Alkylstannanes are organotin compounds in which at least one carbon substituent attached to tin is an alkyl group. They encompass compounds with Sn–C bonds such as alkyl tin hydrides (for example, tributyltin hydride, Bu3SnH) and a broad family of alkyl-substituted organotin reagents of the form R–SnBu3, where R represents an alkyl or aryl group. The tin center in widely used reagents can bear three butyl substituents, especially in Stille-type chemistry, while Bu3SnH serves as a radical hydrogen donor in various transformations.

Preparation methods are diverse. Alkylstannanes can be formed by hydrostannylation of alkenes using Bu3SnH, yielding alkyl–SnBu3 species such as R–CH2–SnBu3. They can also be generated via tin–halide exchange or transmetalation from other organometallic reagents to produce R–SnBu3 or related stannanes, which then serve as cross-coupling partners.

Reactions and applications: A central use of alkylstannanes is in Stille cross-coupling, where an alkyl or aryl group is transferred from R–SnBu3 to an organopalladium intermediate to form new carbon–carbon bonds under palladium catalysis. Alkylstannanes participate in radical hydrostannylation and other tin-mediated functionalizations, providing access to diverse frameworks. The robustness and functional-group tolerance of tin–carbon bonds contribute to their utility in complex molecule synthesis, though toxicity and tin residues require careful handling and disposal.

Safety and handling: Organotin compounds are relatively toxic and can persist in the environment. Proper protective equipment, good laboratory ventilation, and appropriate disposal of tin-containing waste are essential to mitigate hazards.