The Ring Opening of Oxabicyclic Compounds Controlled by a Phenylsulfonyl Group. Synthetic Applications.

Abstract

Oxabicyclic compounds are valuable intermediates for the synthesis of a large array of interesting structures on the biological or pharmaceutical point of view. In this way a key transformation in many synthesis using oxabicyclic intermediates is the cleavage of the oxigen bridge to produce functionalized cyclohexane or cycloheptane derivatives. In order to make this transformation synthetically useful, and introduction of an element of regio- and stereocontrol in the rigid skeleton has been proved to be necessary. A phenylsulfonyl functionality attached to the double bond of the oxabicyclic derivatives render this transformation totally regio- and stereoselective through two different methodologies: a) Michael addition-ring opening sequence and b) strain directed ring opening reaction. Synthetic applications of both methods including the synthesis of carbasugars, cyclitols, alcaloids and polypropionate fragments will be presented and discussed.