Stereospecific Palladium/Copper Cocatalyzed Cross-Coupling of α-Alkoxy- and α-Aminostannanes with Acyl Chlorides

Stille-type cross-coupling between α-alkoxy(amino)stannanes and acyl chlorides affords α-hetero-substituted ketones in moderate to good yields when cocatalyzed by Pd and Cu(I) salts. The reaction is applicable to a wide range of tin compounds, especially those bearing α-electron-withdrawing groups such as benzoyloxy or acetyloxy, although some ethers (e.g., MOM) are also satisfactory. Aromatic acid chlorides give the best yields. Coupling of chiral α-alkoxystannanes, readily available by BINAL-H asymmetric reduction of acylstannanes, proceeds with retention of configuration.