The proposal describes the development of synthetic organic methodology in the area of [3 + 2] annulations involving allyl silanes. These annulations involve the formation of a tertiary carbocation followed by an energetically unfavorable 1,2-silyl shift to the tertiary carbocation, forming a secondary carbocation, followed by cyclization to form five-membered rings. Experiments have been designed to explore the cases where the silyl shift occurs under exothermic conditions (secondary carbocation to tertiary) and under thermoneutral conditions where the silyl migration occurs between two tertiary carbocations. These reactions can be used to establish up to three tetrasubstituted stereocenters in the molecule. Substituent effects as well as the type of electrophile used in the annulation will be explored to gauge the limitations of the [3 + 2] annulation. Forming several stereogenic tetrasubstituted carbons in medicinally important synthetic targets in a single step is attractive and thus several natural products will also be synthesized.
NIH ExPorter
NIH ExPorter