8-epi-Swainsonine

Pinto and co-workers have synthesized various thioniabicyclo[4.3.0]nonanes via a protocol that involves intramolecular displacement of a leaving group on a pendant acyclic chain by cyclic thioethers. A sulfonium ion analogue 54 of swainsonine <2006CAR1685> and an analogue 55 of epi-swainsonine <2006JOC1262>, which differs from swainsonine in the stereochemistry at C-3, were synthesized using this approach. 

Preparations of bicyclic sulfonium ions (e.g., 175) utilize intramolecular alkylation of the tosylate precursor as exemplified in Scheme 104 <1996TA2567>. A sulfonium ion analogue 176 of swainsonine <2006CAR1685> and an analogue 177 of epi-swainsonine <2006JOC1262> were synthesized using a similar approach . 

Nath, M., Mukhopadhyay, R., Bhattacharjya, A. (2006). Divergent cycloaddition and ring-closing metathesis approaches to indolizidine and pyrrolo[l,2-a]azepine skeletons from a chiral precursor an expeditious route to (-)-8-epi-swainsonine triacetate. Organic... 

Aggarwal and Bi proposed the synthesis of 8a-epi-swainsonine (222) from hemiaminal 218 which was prepared from the protected amine 217 in the aza-Achmatowicz reaction as shown in Scheme 42/ The heterocyclic derivative 218 was, under the acidic conditions, transformed into the acetal the carbonyl group was then reduced, under the Luche conditions, providing derivative 219 as practically single isomer. Reduction of the double bond with simultaneous removal of the Cbz group and cleavage of the N,0-acetal afforded piperidine 220 which was easily transformed, via 221, into 8a-epi-swainsonine 222. 

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