100113-45-9Relevant articles and documents
High- and Low-Potential Flavin Mimics. 3. 3,7,10-Trimethyl-(1H,3H,5H,7H,9H,10H)-pyrimidopteridine-2,4,6,8-tetrone-Mediated Reduction of Carbon-Carbon Double Bond α-β to an Acyl Function
Skibo, Edward B.,Bruice, Thomas C.
, p. 1650 - 1659 (1986)
The reduction of the carbon-carbon double bond of maleimide (MI), N-methylmaleimide (NMM), ethyl fumarate, diethyl fumarate, diethyl maleate, fumaric acid, and maleic acid was investigated by employing the low redox potential flavin mimic 3,7,10-trimethyl-(1H,3H,5H,7H,9H,10H)-pyrimidopteridine-2,4,6,8-tetrone (PPTH2) as the reductant.The reaction of these substrates with PPTH2 to produce PPTox and the corresponding succinimide or succinate consists of three processes.The first process occurs on mixing and pertains to the formation of a mixture of N(1)- and C(4a)-substrate adducts of PPTH2.The other two processes, which are kinetically distinguishable, pertain to the breakdown of each of these adducts to PPTox and the reduced substrate.Breakdown of the C(4a)-adduct is catalyzed by hydroxide and is independent of substrate concentration.Hydroxide catalysis is proposed to represent a concerted process whereby the hydroxide abstracts the N(5)-proton while the anionic reduced substrate is departing (Bronsted β approaching 1.0).Breakdown of the N(1)-adduct to the observed products is substrate-dependent pertaining to the rate-determining formation of the N(9),C(4a)-diadduct.In a fast step, base-catalyzed elimination from the C(4a)-position of the latter provides the reduced substrate anion and the N(9)-monosubstrate adduct of PPTox.Rapid dissociation of the N(9)-adduct then provides PPTox.It is concluded that the reduction of a carbon-carbon double bond to an acyl function by the low-potential flavin mimic proceeds via C(4a)-adducts.This conclusion and the principle of microreversibility infers that enzyme-bound flavins of high potential, as in dehydrogenating flavoenzymes, may oxidize succinates to fumarates via C(4a)-adducts.
