Synthesis of α,β-Unsaturated Spirolactams by Intramolecular Cyclization of Endocyclic N-Acyliminium Ions

Article abstract of DOI:10.1016/0040-4039(95)01568-3

The synthesis of (+/-)-6-benzyl-3-methyl-3-en-1,6-diazaspiro<4.5>decane-2,7-dione (18), the spiro moiety of (+/-)-pandamarine has been achieved by oxidative cyclization of the (Z) and (E) isomers of 5-(N-benzyl-4-carboxamido-butylidene)-3-methyl-3-en-pyrrolin-2-one (15a) and (15b).The stereoselectivity exhibited in the intramolecular cyclization by both butylidene precursors has also been discussed.