Abstract
Lewis acid promoted cascades of a tris(disubstituted epoxide) triggered by silver-promoted abstraction of a bromide ion favors trans -dioxabicyclo[4.3.0]nonanes, rather than diads or triads of tetrahydropyrans (trans -dioxabicylco[4.4.0]decanes, for example). These results suggest that an epoxide-attacking-epoxonium mechanism is not operative in this system.
Key words
epoxides - cascade - ring opening - fused-ring systems - Lewis acids
References and Notes 1 Current address: Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA.
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