Total Synthesis of (−)-Kaitocephalin

[reaction: see text] Total synthesis of the potent AMPA/KA receptor antagonist (-)-kaitocephalin (1) and its three diastereomers has been accomplished. The synthesis features strictly substrate-controlled operations to alpha-formylglutamate 3 starting with alpha-hydroxymethylglutamate 4. The requisite 2R,3S,7R-stereocenters were efficiently constructed by manipulation of stereoselective reactions: dihydroxylation of 7 followed by azide substitution of the corresponding thionocarbonate 10 and Cu-mediated allylation of an acyliminium ion 21. All of the protecting groups in 26 were removed simultaneously by AlCl3/Me2S to give 1.