The Naturally Occurring 3-Piperideines

Ugryumov, Dokl. Akad. Nauk SSSR 29, 48 (1940) Chem. Abstr. 35, 3644 (1941). 

150 Nopco Chem. Comp., British Patent 646,220 (1950) Chem. Abstr. 45, 2986 (1951). 

In the synthesis of guvacine (169a), ethyl l-benzoyl-4-piperidone-3-carboxylate (171) was used as the key intermediate.161 

Racemic baikiain can be obtained by an electrolytic reduction of picolinic acid60 (see Section II, B, 2), by an eight-step synthesis from l-benzoyloxy-4-bromo-2-butyne163 or, more simply, from cis-1,4-dichloro-2-butene (175).164 

Anatabine (177) and A -methylanatabine are minor alkaloids of tobacco.1 5-167 Racemic 177 was synthesized by the BF3-catalyzed condensation (cf. Section II, A) of diethyl 3-pyridylmethylenebis-carbamate (176) with 1,3-butadiene and subsequent removal of the JV-ethoxycarbonyl group.168,169 

---