Southern Research Station

Title: Condensed tannins. Base-catalysed reactions of polymeric procyanidins with phloroglucinol: Intramolecular rearrangements

Author: Laks, Peter E.; Hemingway, Richard W.; Conner, Anthony H.

Date: 1987

Source: Journal of the Chemical Society Perkin Trans. I. 1875-1881

Description: Reactions of polymeric procyanidins with phloroglucinol at pH 12.0 and temperatures of 23 or 50°C gave epicatechin-(4β)-phloroglucinol (7), by cleavage of the interflavanoid bond between procyanidin units with subsequent addition of phloroglucinol, and (+)-catechin from the terminal unit. The phloroglucinol adduct (7) rearranged to an enolic form of 8-(3,4-dihydroxyphenyl)-7-hydroxy-6-(2,4,6-trihydroxyphenyl)bicyclo[3.3.1]nonane-2,4,9-trione (9). Rearrangement of a dimeric procyanidin phloroglucinol adduct resulted in the formation of 3'-{8-(3,4-dihydroxyphenyl)-7-hydroxy-2,4,9-trioxobicyclo[3.3.1]nonan-6-yl}-4-(3,4-dihydroxyphenyl)-2',3,4',5,6',7-hexahydroxyflavan (10), also in an enolic form. (+)-Catechin, from the terminal unit, gave catechinic acid, an enolic form of 6-(3,4-dihydroxyphenyl)-7-hydroxybicyclo[3.3.1]nonane-2,4,9-trione (4).

Keywords: 

View and Print this Publication (1.7 MB)

Publication Notes: 

• We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
• This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.

 Get the latest version of the Adobe Acrobat reader or Acrobat Reader for Windows with Search and Accessibility

Citation

Laks, Peter E.; Hemingway, Richard W.; Conner, Anthony H.  1987.  Condensed tannins. Base-catalysed reactions of polymeric procyanidins with phloroglucinol: Intramolecular rearrangements.   Journal of the Chemical Society Perkin Trans. I. 1875-1881