The reaction of allyl stannanes with CO2 to form stannyl carboxylates (esters) is catalyzed by Pd(PR3)4 complexes. Thus, R3SnCH2CH=CH2 [R=Me and Ph]are converted to R3SnO2 CCH2CH=CH2 and R3SnO2CCH=CHCH3 under 33 atm of CO2 (70°C, THF) in moderate to excellent yield in the presence of 8 mol% Pd(PPh3)4 ; polycarboxylation of diallyldibutyltin and tetraallyltin also is effected, producing the respective di- and tetracarboxylates, Bu2Sn(O2CCH2CH=CH2)2 and Sn(O2CCH2 CH=CH2)4 , along with the corresponding isomeric crotyl derivatives. In the presence of allyl halides, allyl stannanes and CO2 undergo carboxylative coupling to produce allyl esters. Under these conditions other Sn-C (Sn-alkyl, -aryl, -vinyl) and Si-C (Si-allyl, -alkyl, -aryl, -vinyl) bonds are inert to carboxylation and carboxylative coupling with allyl halides. A tentative mechanism is proposed to account for this catalytic carboxylation of a main group metal-carbon bond.
Franks, Russell J., "Palladium-Catalyzed Carboxylation of Allyl Stannanes and Carboxylative Coupling of Allyl Stannanes and Allyl Halides [Abstract]" (1998). Faculty Publications. 31.