Regiospecific Displacement of the C‐B Bond of Tris[4‐(substituted)furan‐3‐yl]boroxines with C‐Sn Bond and C‐O Bond: Syntheses of 3,4‐Disubstituted Furans and 4‐Substituted‐3(2H)‐furanones ,

Tris[4‐(substituted)furan‐3‐yl]boroxines 2 , prepared from the corresponding 4‐(substituted)‐3‐(trimethylsilyl) furan 1, were converted successfully to 4‐(substituted)‐3‐(tributylstannyl)furans 3 through palladium‐catalyzed cross‐coupling reactions with tributylstannyl chloride. Palladium‐catalyzed cross‐coupling reactions of 3 with organohalides afforded 3,4‐disubstituted furans 4 . Regiospecific iodination of 4‐(trimethylsilyl)‐3‐((tributylstannyl) furan ( 3a ) gave 4‐iodo‐3‐(trimethylsilyl)furan ( 5 ), which reacted with excess ethyl acrylate under a common Heck‐condition to produce 2,3‐bis( trans ‐ethoxycarbonylvinyl)‐4‐(trimethylsilyl)furan ( 6 ). A thermal 6‐electrocyclic reaction followed by dehydration converted 6 into benzo[2,3‐6]furan 8 . Oxidation of 2 generated the corresponding 4‐substituted‐3(2H)‐furanones 9 .