Divergent Cycloaddition and Ring-Closing Metathesis Approaches to Indolizidine and Pyrrolo[1,2-<i>a</i>]azepine Skeletons from a Chiral Precursor: An Expeditious Route to (−)-8-<i>epi</i>-Swainsonine Triacetate
[reaction: see text] A divergent strategy for the synthesis of diverse azabicyclic ring systems has been developed in which a chiral N-allylpyrrolidine derivative, obtained from a carbohydrate precursor was converted to (-)-8-epi-swainsonine triacetate by RCM and to a pyrrolo[1,2-a]azepine derivative and a 3-hydroxymethyl-substituted indolizidine by N-allylcarbohydrate nitrone and nitrile oxide cycloadditions
Regioselective synthesis of chiral six- and seven-membered N-heterocycles from N-allyl carbohydrate nitrones: Tuning of regioselectivity by N-substitution
The intramolecularcycloaddition of N-allyl carbohydrate nitrones leads to enantiomerically pure six- and seven-membered nitrogen heterocycles and the regioselectivity of the cycloaddition was controlled by changing the substituent on the nitrogen atom of the N-allyl moiety.