R. Lavilla et al., Iodocyclisation of 1,4-dihydropyridines; Synthesis and reactivity of 1-iodoindolo[2,3-alpha]quinolizidines, EUR J ORG C, (11), 1999, pp. 2997-3003
The addition of iodine (or related species) to beta-acyl-N-alkyl- 1,4-dihyd
ropyridines which possess an N-substituent with an appropriate nucleophile
moiety, leads to the 3-iododihydropyridinium ions, which undergo an interna
l nucleophilic attack to give, regio- and stereoselectively, the iodobi(pol
y)heterocyclic ring systems 2a-f in good yields. Reactivity studies on the
iodoindolo-quinolizidines 2e,f lead to the pentacyclic cyclopropane systems
4a,b, azides 5 and 6, norderivative 9 and, by a base-corresponding induced
elimination, dihydropyridine 10, a precursor of the zwitterionic alkaloids
flavopereirine and 6,7-dihydroflavo-pereirine.