CARBOHYDRATES TO CARBOCYCLES - SYNTHESIS OF THE DENSELY FUNCTIONALIZED CARBOCYCLIC CORE OF TETRODOTOXIN BY RADICAL CYCLIZATION OF AN ANHYDRO SUGAR PRECURSOR
Ra. Alonso et al., CARBOHYDRATES TO CARBOCYCLES - SYNTHESIS OF THE DENSELY FUNCTIONALIZED CARBOCYCLIC CORE OF TETRODOTOXIN BY RADICAL CYCLIZATION OF AN ANHYDRO SUGAR PRECURSOR, Journal of the American Chemical Society, 115(15), 1993, pp. 6666-6672
The core of tetrodotoxin is a densely functionalized carbocycle for wh
ich an annulated pyranose can be envisaged as a retron. The carbocycli
c ring is constructed upon a rigid 1,6-anhydro template which permits
the early introduction of the key angular nitrogen, and concomitantly
positions a trap for reaction with a carbon-centered radical generated
chemospecifically at C6. The carbocyclic entity is elaborated in this
process leading to a caged system with the capability for generating
all of the stereogenic centers. A novel procedure using tert-butylhypo
nitrite is described for C6 dehydrogenation pursuant to the intramolec
ular radical cyclization.