Natural 2,6-Dialkyl-3-piperidinols. 9. Total Synthesis of (+/-)-Prosafrinine and 13C NMR Studies of Some Analogous Compounds

Article abstract of DOI:10.1246/bcsj.62.1321

1,7-Dibromoheptane was used to alkylate both ketoesters 2 and 4 successively.Hydrolysis and decarboxylation of the resulting intermediate afforded the ethylenic diketone (6).Ozonolysis of the double bond of 6 gave the diketonic aldehyde (8).Alkaline condensation of nitroethane on the aldehydic carbonyl of the latter, followed by hydrogenation using a Pd-Pt catalyst, afforded 3-r-hydroxy-6-c-(10-oxododecyl)-2-c-methylpiperidine <(+/-)-prosafrinine> (1a) and (+/-)-3-epiprosafrinine (1b).The structures of 1a, 1b, and some analogues were confirmed by 13C NMR studies.