Dehydrogenative Polymerization of 3,5-Disubstituted p-Coumaryl Alcohols

Abstract

3,5-Disubstituted p-coumaryl alcohols (3-methoxy-5-iodo-, 3,5-diiodo-, 3-methoxy-5-nitro-, 3,5-dinitro-, 3,5-dimethoxy- and 3,5-dimethyl-p-coumaryl alcohols) were synthesized and dehydrogenated to their dimeric compounds with ferric chloride in dioxane (nonpolar solvent) and acetone-water (polar solvent), respectively. Yields of the β-ethers were, for example, 85 % (sinapyl alcohol) and 86 % (3, 5-diiodo-p-coumaryl alcohol) in dioxane, and 11% (the former) and 80 % (the latter) in acetone-water, respectively. These results suggest that the most effective factor in the radical coupling of these alcohols is the electronic effects of the substituent groups, but not the steric hindrance. Syringylglycerol-β-sinapyl ether was obtained in a high yield from sinapyl alcohol when dioxane was used as a solvent.