Orgy, maybe the se is a little thin when it comes to literature refs.Â
Ritter, Cyrax, Blondie, PP were some bees interested in this.
Michael Condensation
methyl or ethyl acrylate with amine (pea), in alcohol or (possibly) without solvent.
Dieckmann Cyclization
cyclisation with sodium hydride or sodium metal in benzene or toluene alternatively with strong base Kt-BuO -forgotten the solvent. also phase transfer possibilities
Post 307716 (missing)
(Rhodium: "michael condensation", Chemistry Discourse) - example of the Michael addition
https://www.thevespiary.org/rhodium/Rhodium/pdf/isocarfentanil2.pdf
isocarfentanil - fentanyl with a 3-carbomethoxy moiety (ie no hydrolysis step) prepped with PEA and acrylate followed by cyclisation
Post 308217 (missing)
(Ritter: "hydroolysis of carboalkyl group", Chemistry Discourse) - hydrolysis of the 3-carboalkoxy group
the route to 4-subst-piperidones via route discussed is not really speculative -and is well covered in the literature. i have some photocopied JOC, JACS stuff on piperidone synthesis mostly old - 1950's/60's but not at my present location. sort of lost interest in this stuff when decided that anilino-piperidines dont compare with the morphine based stuff when it comes to euphoirc potential - no interest in dissociatives