PHENOLATION OF (-CATECHIN WITH MINERAL ACIDS - II - IDENTIFICATION OFNEW REACTION-PRODUCTS())

To investigate the reactions that occur in the flavanoid unit during t he liquefaction of tannin in phenol, the phenolysis of (+)-catechin wa s studied using either H2SO4, HCl, Or BF3 . 2H(2)O as acid catalyst. I n addition to roxy-3-(4-hydroxyphenyl)propyl]-1,3,5-benzenetriol (1) a nd droxyphenyl)methyl]-2,3-dihydro-4,6-benzofurandiol (3) that have be en described previously, eight additional reaction products were isola ted, four of which were compounds that have not been described previou sly. The novel compounds described here are: roxy-3-(2-hydroxyphenyl)p ropyl]-1,3,5-benzenetriol (2), droxyphenyl)methyl]-2,3-dihydro-4,6-ben zofurandiol (4), dihydro-7-(4-hydrophenyl)methyl-4,6-benzofurandiol (5 ), and 2,3,5,6-tetrahydrobenzo[1,2-b:5,4-b']-difuran-4-ol (6). The str uctures of these and other previously described products are consisten t with opening of the pyran ring of catechin and reaction at C-2 by ei ther the para or the ortho position of phenol. Additional products res ulting from reaction between pyran ring cleavage products and catechin , and from reaction of cleavage products were found. Similar reactions would be expected to take place during the phenolysis of condensed ta nnins.