Hydrogenolysis of enol triflates; A new method for the reduction of ketones to methylene compounds

Total synthesis of dendrobate alkaloid (+)-241D, isosolenopsin and isosolenopsin A: application of a gold-catalyzed cyclization

“…The cis-stereochemistry was easily confirmed by NOE experiment and is in accordance with the results we previously reported. 3 These piperidones 12 and 13 were converted to the 2,6-disubstituted piperidines 16 and 17 by formation of a mixture of enol triflates (14,15) followed by a catalytic hydrogenation 17 in 94 and 96% yield respectively over the two-step sequence. 18 In the last step, treatment with HCl afforded the targets isosolenopsin alkaloids as hydrochloride salts in the insoluble part.…”

A Novel Approach to the Enantioselective Synthesis of Nuphar Alkaloids: First Total Synthesis of (−)-(5S,8R,9S)-5- (3-Furyl)-8-methyloctahydroindolizidine and Total Synthesis of (−)-Nupharamine

“…The deoxygenation was then achieved in one step by NaBH 3 CN reduction of the in situ generated tosylhydrazone of 6 to obtain compound 7 with a poor 33% yield . Nevertheless, better results were obtained in a two-step procedure by formation of an enoltriflate followed by catalytic hydrogenation in the presence of PtO 2 , which afforded bicyclic carbamate 7 in 85% yield (based on 70% conversion of 6 ). At this point, hydrolysis of the carbamate moiety of compound 7 employing anhydrous t -BuOK in THF afforded the desired piperidine 8 .…”

Total Synthesis of (±)-Batrachotoxinin A

“…In the event, deprotection of the primary silyl ether using TASF, followed by trapping with PhNTf 2 , afforded the desired Michael-adduct 12 in 95% yield. Hydrogenolysis of the enol triflate could be achieved using platinum oxide and hydrogen to provide, after further manipulations, triketone 13 in good yield.…”