Total synthesis of furan and thiophene analogs 6 and 7 of duocarmycin SA was achieved in racemic forms, starting from methyl 4, 5-dibromo-2-furan-and thiophenecarboxylates (15a and 15b). Lithio derivatives 12a (a series: X= O) and 12b (b serie: X= S) were reacted with the aldehyde 22 for preparation of 25a and 25b, and successive synthetic operations, including Heck reaction of 25a and 25b to obtain 26a+ 27a and 26b+ 27b, and B ring ...
