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.