Ring-closing metathesis in flavonoid synthesis, part 1: flavenes.

Tebbe methylenation and ring-closing metathesis with Grubbs second generation catalyst were investigated as key steps in the synthesis of flav-2-enes with natural substitution patterns. The effect of aromatic substituents on the electron densities of the allyl and vinyl moieties and the effect thereof on methylenation and ringclosing metathesis, is discussed. [ABSTRACT FROM AUTHOR]