Bioactive Phytochemicals: Efficient Synthesis of Optically Active Substituted Flav-3-enes and Flav-3-en-3-o-R Derivatives

Scheme 2

Mesylation and tosylation of flavan-3-ol. Reagents and conditions: (i) imidazole, THF, 1-toluenesulfonyl chloride, ice bath, (ii) step (i), methyl triflate, ice bath; (iii) 8 or 9, THF, N-methylimidazole, step (ii), rt, 24 h, 82%; (iv) 8, MsCl, DMAP, THF, Et3N, rt to −5°C, 99%.