Cascading Radical Cyclization of Bis-Vinyl Ethers: Mechanistic Investigation Reveals a 5-exo/3-exo/retro-3-exo/5-exo Pathway
2012
O’Rourke, Natasha F. | Davies, Katherine A. | Wulff, Jeremy E.
We recently described an iterative synthesis of oligo-vinyl ethers, followed by a radical cascade to provide a family of hexahydro-2H-furo[3,4-b]pyrans. Our results for the radical cascade were consistent with either a direct 6-endo-trig addition of a vinyl radical onto the first vinyl ether function or an initial 5-exo-trig addition, followed by rearrangement to the more stable anomeric radical intermediate. In this report, we describe our further mechanistic studies aimed at distinguishing between these two possibilities and conclude that the 5-exo/3-exo/retro-3-exo pathway is dominant.
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