Cycloaddition reactions are useful for constructing complex cyclic molecular scaffolds with excellent atom economy. Although much is known about the Diels-Alder reaction and some 1,3-dipolar cycloaddition reactions (i.e. Click Chemistry), the [5+2] cycloaddition reaction has not been nearly investigated as much. We have developed an enantioselective [5+2] cycloaddition reaction using oxidopyrylium ylide dipoles with iminium-activated α,β-unsaturated aldehyde dipolarophiles. This is the first catalytic enantioselective dipolar cycloaddition of the oxidopyrylium species with electron poor alkenes. The 8-oxabicyclo[3.2.1]octane product is formed with excellent enantioselectivity. The product's architecture can be seen in a variety of natural products and bioactive compounds.

Enantioselective [5+2] cycloaddition of oxidopyrylium ylides by iminium catalysis

251st National Meeting (2016)

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