Tyrosinase catalysed biphenyl construction from flavan-3-ol substrates

Mushroom tyrosinase catalysed oxidation of three flavan-3-ols, viz. catechi n, fisetinidol and mesquitol, was conducted to construct biphenyl bonds. Ex posure of the flavan-3-ols to tyrosinase and subsequent trapping of the o-q uinone intermediates resulted in the formation of novel flavan-3-ol derivat ives, the structures of which were elucidated by mono- and two-dimensional H-1-NMR experiments. Application of the methodology resulted in the improve d synthesis of the natural flavan-3-ol dimer, mesquitol-[5 --> 8]-catechin, previously isolated from Prosopis glandulosa. (C) 2000 Elsevier Science Lt d. All rights reserved.