addition-cyclization of oxime ethers and hydrazones intramolecularly connected with the alpha,beta-unsaturated carbonyl group is described. The radical reaction of oxime ethers 1, 2, and 4 connected with acryloyl and methacryloyl moieties proceeded smoothly to give the heterocycles via a tandem C-C bond-forming process. The tandem reaction of hydrazone 5 took place in the presence of Zn(OTf)(2) as a Lewis acid to give
The radical addition-cyclisation of alpha, beta-unsaturated hydroxamates containing an oxime ether provides a novel method for the stereoselective synthesis of amino-1,2-oxazinones. Its synthetic utility is demonstrated by a stereoselective synthesis of beta-amino acid derivatives, such as alpha-alkyl-beta-amino-gamma-lactone and alpha,beta-disubstituted beta-lactam.
The radicaladdition-cyclizationreaction of substrates having two different radical acceptors such as acrylate and aldoxime ether moieties was studied. This new free radical-mediated Mannich-type reaction proceeded smoothly via a tandem C-C bond-forming process. Furthermore, the diastereoselective tandemreaction provides the novel method for asymmetric synthesis of gamma-butyrolactones and beta-amino
Asymmetric Self- and Cross-Aldol Reactions of Glycolaldehyde Catalyzed by D-Fructose-6-phosphate Aldolase
作者:Xavier Garrabou、José A. Castillo、Christine Guérard-Hélaine、Teodor Parella、Jesús Joglar、Marielle Lemaire、Pere Clapés
DOI:10.1002/anie.200902065
日期:2009.7.13
facets of enzyme activity: D‐Fructose‐6‐phosphate aldolase (FSA) catalyzes the self‐aldolreaction of glycolaldehyde (GA) and its cross‐aldol addition to other aldehydes. As the affinity of GA for FSA as a donor is higher than that as an acceptor, cross‐aldolreactions are possible with good to poor aldehyde acceptors if the concentration of GA in the reaction is kept low.