title: Towards stereochemical control: A short formal enantioselective total synthesis of pumiliotoxins 251D and 237A.
abstract: A concise enantioselective synthesis of the advanced intermediate 5 for the synthesis of pumiliotoxins (Gallagher's intermediate) is described. The synthesis started from the regio- and trans-diastereoselective (dr = 98:2) reductive 3-butenylation of (R)-3-(tert-butyldimethylsilyloxy)glutarimide 14. After O-desilylation and Dess-Martin oxidation, the resulting keto-lactam 10 was subjected to a highly trans-stereoselective addition of the methylmagnesium iodide to give carbinol 11 as sole diastereomer. An efficient ring closure procedure consisting of ozonolysis and reductive dehydroxylation provided the indolizidine derivative 5, which completed the formal enantioselective total synthesis of pumiliotoxins 251D and 237A.
authors.affiliation: Department of Chemistry and Fujian Provincial Key Laboratory of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005, P. R. China.
authors.forename: Jie
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Department of Chemistry and Fujian Provincial Key Laboratory of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005, P. R. China.
authors.forename: Hong-Kui
authors.initials: HK
authors.lastname: Zhang
authors.affiliation: Department of Chemistry and Fujian Provincial Key Laboratory of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005, P. R. China ; State Key Laboratory of Applied Organic Chemistry Lanzhou University, Lanzhou 730000, P. R. China.
authors.forename: Pei-Qiang
authors.initials: PQ
authors.lastname: Huang
keywords: Grignard reagent; enantioselective synthesis; pumiliotoxin 237A; pumiliotoxin 251D; reductive dehydroxylation; ring closure; trans-methylation