230618-38-9Relevant academic research and scientific papers
The high stereoselectivity of the tandem sequence Diels-Alder reaction/Ireland-Claisen rearrangement starting from substituted O-(E)-buta-1,3-dienyl ketene acetals and cyclic dienophiles
Soldermann, Nicolas,Velker, Joerg,Neels, Antonia,Stoeckli-Evans, Helen,Neier, Reinhard
, p. 2379 - 2387 (2007)
A new tandem reaction leads to bicyclic cyclohexene derivatives with complete control of the relative configuration of the four chiral centers formed. The high diastereoselectivity is the consequence of an endo-selective Diels-Alder reaction followed by an Ireland-Claisen rearrangement that proceeds via a boat-like transition state. Georg Thieme Verlag Stuttgart.
Studies on the mechanism of action of 2-formyl-4-pyrrolidinopyridine: Isolation and characterization of a reactive intermediate
Sammakia, Tarek,Hurley, T. Brian
, p. 4652 - 4664 (2007/10/03)
This paper describes the mechanism of action of 2-formyl-4- pyrrolidinopyridine (FPP, 1a) which is a catalyst for the hydroxyl-directed methanolysis of α-hydroxy esters. This species was initially designed to act as a nucleophilic catalyst; however, we have ruled out a nucleophilic mechanism by examining the activity of 6-substituted-FPP derivatives. These compounds are more hindered in the vicinity of the pyridine nitrogen than FPP itself but are also more active catalysts. Furthermore, the presence of p- nitrophenol, a mild acid, was found to accelerate the catalytic reaction. These results are inconsistent with a nucleophilic catalysis mechanism. We provide evidence that the reaction instead proceeds via dioxolanone intermediate 10. Dioxolanone 10 can be obtained by treating either the p- nitrophenyl ester or the pentafluorophenyl ester of glycolic acid with FPP in chloroform in the absence of methanol. It has been isolated, characterized, and shown to be kinetically competent when subjected to the conditions of the catalytic reaction.
