Novel ring forming reactions for organic synthesis

Abstract

<p>Almost all biologically important molecules contain a ring in their structure. The first two sections of this manuscript deal with general methodology which will facilitate the construction of certain rings. The last part of this manuscript deals with the total synthesis of a natural product containing a tricyclic structure;Part I deals with the preparation of cyclic 1,2-aminoalcohols. Many important natural products contain this substructure. Several recent synthetic methods have been reported for the synthesis of 1,2-aminoalcohols, attesting to the high interest in this area and also to the need for additional methods. Part I deals with the cycloaddition of dienes with E-1-benzoyloxy-2-nitroethene. The nitro group is then reduced to yield the cyclic 1,2-aminoalcohols;Part II deals with the intramolecular cyclization of cyclic hemiketals with alkenes to yield bicyclic ketals. This reaction proceeds via an alkoxy radical. Many important natural products such as the ginkolides contain the bicyclic ketal moiety. Research is in progress on the application of this methodology to the total synthesis of these biologically important natural products;The last part of this manuscript deals with the total synthesis of a 9-hydroxy substituted iridoid, which was recently isolated from Gelsemium Sempervirens.</p>