1. Chromium(0)- Promoted Higher Order Cycloaddition Reactions: Studies Toward The Total Synthesis Of The Cyclocitrinols And Echinopines A And B 2. Total Synthesis Of (±)-Debromoflustramine B Via [4+1] Cyclization Of An Indole Isocyanate And A Bis(alkylthio)carbene

<p>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.</p> <p>A Bronsted acid catalyzed rearrangement of the 11-trimethylsilyl-tetracyclo[8.1.0.03,7.04,11]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.</p> <p>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.</p> <p>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.</p>

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Open Access Dissertation

Discipline thesis:degree_discipline

Chemistry

Year dc:date.available

2013

Author dc:creator

• De, Saptarshi

Contributors dc:contributor

• James H. Rigby

• [4+1] cyclization
• Cyclocitrinols
• Debromoflustramine B
• Echinopines A and B
• Higher-order cycloaddition Reactions
• Chemistry
• Organic Chemistry

Repository record dc:identifier

https://digitalcommons.wayne.edu/oa_dissertations/649

OAI identifier oai:identifier

oai:digitalcommons.wayne.edu:oa_dissertations-1648