Arynes are generated cleanly and rapidly by halogen-lithium exchange of ortho-haloaryl triflates with n-BuLi at -78-degrees-C. [2+4]-Cycloaddition of alpha-alkoxyaryne with 2-methoxyfuran proceeded regioselectively (head-to-head) to afford 1,4,5-naphthalenetriols.
Total synthesis of antibiotic C104: Benzyne-Furan cycloaddition approach to the angucyclines
First totalsynthesis of antibiotic C104 (1), a prototypical member of the angucyclines, was accomplished. Highly regioselective cycloaddition of α-alkoxybenzyne 12 with angularly fused α- siloxyfuran 10 enabled the straightforward construction of the characteristic benz[a]anthraquinone framework. The D-olivosyl C-glycoside was introduced via the O → C-glycoside rearrangement in a regio- and stereoselective