494225-07-9Relevant academic research and scientific papers
Towards stereochemical control: A short formal enantioselective total synthesis of pumiliotoxins 251D and 237A
Zhang, Jie,Zhang, Hong-Kui,Huang, Pei-Qiang
, p. 2358 - 2366 (2013)
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-(tertbutyldimethylsilyloxy) 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.
Total synthesis of 1-deoxy-7,8a-di-epi-castanospermine and formal synthesis of pumiliotoxin-251D
Sultane, Prakash R.,Mohite, Amar R.,Bhat, Ramakrishna G.
supporting information, p. 5856 - 5858 (2013/01/13)
A concise and efficient synthesis of (6R,7S,8R,8aS)-6,7,8- trihydroxyindolizidine (1-deoxy-7,8a-di-epi-castanospermine) 2 is described. The synthesis employs cross metathesis in building the key intermediate 9 and is used effectively in constructing indol
Synthesis of the bicyclic core of pumiliotoxins
Sudau, Alexander,Muench, Winfried,Bats, Jan-W.,Nubbemeyer, Udo
, p. 3304 - 3314 (2007/10/03)
The bicyclic core of the pumiliotoxins was synthesized in nine to eleven steps starting from L-(-)-proline. This chiral pool starting material was initially converted into an optically active 2-vinylpyrrolidine by standard operations. The first key step allowed the generation of a nine-membered ring lactam by means of a zwitterionic aza-Claisen rearrangement. The 1,4 chirality transfer was found to be low, but the double bond of the azoninone was generated with an exclusive trans configuration in a planar-S arrangement. The mixture of diastereomers thus obtained was immediately epoxidized; the planar chiral information could be completely used to build up new stereogenic centers. Subsequent ring closure under hydrogenolytic conditions resulted in the formation of the bicyclic core with a bridgehead of defined configuration. The hydroxyl group of that material could be protected as a TBS ether, or alternatively a sequence of a Swern oxidation and subsequent methyl Grignard addition gave the complete bicyclic framework with low C8 diastereoselectivity. Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002.
