N-Protected b-propargylamino acrylic estersw ith ap ush-pull olefinic bonda ffordedg ood to high yields of dihydropyridines upont reatment with 5% tris(2-furyl)phosphine-gold(I) chloride/silver(I) tetrafluoroborate [(TFP)AuCl/AgBF 4 ]i na nhydrousb enzene.C arbamate and sulfonyl groups were employed for nitrogen protection. On am odel enyne, the p-methoxybenzenesulfonyl (MBS) group was found to be ab etter protective group than tosyl in termso fc yclization yield, and also the yield of elimination to the corresponding 2,3,4-trisubstituted pyridines.B oc-protectedd ihydropyridines underwent partiald eprotection/oxidationu nder the cyclization conditions,w hich enabled am ore straightforward, one-pot preparation of the corresponding pyridines. In another application, an appropriately substituted derivative protecteda sastablem ethoxycarbamate was subjected to catalytic hydrogenation affording the known precursor of paroxetine.T he chemoselectivity of enynec yclization (dihydropyridine vs. pyrrole) is governed, among other factors,b yC -3 substitution. Dihydropyridinesw ere obtained as sole products regardless of the catalyst/conditions when C-3 was unsubstituted.
A variety of medicinally important multisubstituted tetrahydropyridines, 4-aryl piperidines, isoquinolines and fused pyridines were prepared in 1–3 step sequences via nucleophile-assisted Au(i)-catalyzed cyclizations of easily available azaenynes.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.