Novel heterocyclic betaines relevant to the mechanism of tyrosinase-catalysed oxidation of phenols
作者:John Clews、Christopher A. Ramsden、John Clews、Christopher J. Cooksey、Peter J. Garratt、Edward J. Land、Patrick A. Riley
DOI:10.1039/a706281h
日期:——
Betaines formed by dianisyltellurium oxide oxidation of N,N-dialkyldopamines are identical to the products formed by tyrosinase oxidation of N,N-dialkyltyramines or N,N-dialkyldopamines and provide evidence that tyrosinase does not act as a tyrosine hydroxylase; oxidations of higher homologues of N,N-diethyldopamine are also described.
The evolution of a total synthesis of the exiguamines, two structurally unusual natural products that are highly active inhibitors of indolamine‐2,3‐dioxygenase (IDO), is described. The ultimately successful strategy involves advanced cross‐coupling methodology and features a potentially biosynthetic tautomerization/electrocyclization cascade reaction that forms two heterocycles and installs a quaternary
Oxidative cyclisation of N,N-dialkylcatechol amines to heterocyclic betaines via o-quinones: synthetic, pulse radiolytic and enzyme studies
作者:John Clews、Christopher J. Cooksey、Peter J. Garratt、Edward J. Land、Christopher A. Ramsden、Patrick A. Riley
DOI:10.1039/b006860h
日期:——
tyrosinase oxidation of phenols to o-quinones in which the o-quinone is formed in a single step and not via an intermediate catechol. Similar chemical and enzymatic oxidation of a higher homologue gives an analogous 1,2,3,4-tetrahydroquinolinium-6-olate. Pulse radiolysis studies show that this product is formed via a spiro intermediate and not by direct cyclisation to form the six-membered quinolinium ring