Access Type

Open Access Dissertation

Date of Award

January 2013

Degree Type


Degree Name




First Advisor

James H. Rigby


A facile and short stereoselective synthesis of the functionalized tetracyclic core structure of the cyclocitrinols, a family of unusual C25 steroid isomers, has been accomplished. The key structural unit, the bicyclo[4.4.1]A/B ring system, was constructed by a regioselective Cr(0)-promoted [6π + 4π] photochemical cycloaddition reaction.

A Bronsted acid catalyzed rearrangement of the 11-trimethylsilyl-tetracyclo[,7.04,11]undeca-5,8-diene ring system to the unusual homotriquinacene ring system. The trimethylsilyl substitution on the cyclopropane moiety was found to be crucial for the rapid transformation which is believed to proceed via carbocation intermediates.

A short concise formal synthesis of Echinopines A and B is reported. The key [5.5.7] tricyclic intermediate, which has been previously used for synthesis of Echinopine A and B, was synthesized using a sequence of Cr(0)-promoted photochemical [6p+2p] cycloaddition, followed by a novel radical cyclization with a cyclic conjugated diene, in only five steps.

A novel [4+1] cyclization of an indole isocyante and bis(alkylthio)carbene has been used for an efficient and protecting group free total synthesis of (±)-debromoflustramine B.