Nitrone cycloaddition-based entry to the coccinelline alkaloid skeleton: synthesis of (±)-epi-hippodamine
Abstract
Synthesis of intermediate 13 possessing the perhydropyrido[2,1,6-de]quinolizine skeleton of the coccinelline alkaloids and conversion to epi-hippodamine 20 was accomplished with stereochemical control arising from a key cycloaddition reaction of nitrone 2 with ethyl hexa-3,5-dienoate.