Reactions And Rearrangements Of Hetero Cyclic Nitrogen Compounds

Author : Charles Hamilton Heath
Publisher :
ISBN 13 :
Total Pages : 316 pages
Book Rating : 4.:/5 (816 download)

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Download or read book Synthetic Endeavours in Nitrogen Heterocycles written by Charles Hamilton Heath and published by . This book was released on 2011 with total page 316 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis describes our synthetic endeavours in nitrogen containing heterocyclic compounds. The work included several key themes including the pursuit of biologically active compounds, the development of elegant and environmentally benign procedures including domino reactions. The use of palladium mediated transformations in organic synthesis, the construction of new unknown ring systems and the structural elucidation of heterocyclic compounds including the structural elucidation of natural products by synthesis have also been explored. Chapter 2 describes our synthetic investigations of the 3-benzazepines I and azepino[4,5-b]indoles II. Through the use of the palladium catalysed Tsuji-Trost reaction followed by a Heck reaction we were able to devise a synthetic approach to access these N-heterocycles. We were able to synthesize simple derivatives of both I and II in addition to more complex compounds featuring additional fused rings by including the use of different cyclic and acyclic allylic substrates for the Tsuji-Trost reaction. After the development of the single step Tsuji-Trost/Heck synthetic protocols for these compounds we successfully combined these two reactions into a single pot domino reaction. In addition to Tsuji-Trost/Heck domino reactions we have also developed a Heck/carbopalladation domino reaction for the synthesis of an azepino[3,4,5-hi]benz[b]indolizine derivative. Chapter 3 describes our attempts to synthesize the natural product arboflorine. We initially began with attempts to elaborate the azepino[4,5-b]indoles synthesized in Chapter 2 to provide arboflorine, however this did not prove fruitful. In the course of this investigation we discovered a novel rearrangement of an azepino[4,5-b]indole to give the peroxide IV which became the topic of Chapter 4. We attempted to further elaborate other known azepino[4,5-b]indoles via a variety of methods including inter and intramolecular Heck reactions, radical chain reactions and functionalization via an iminium salt. These attempts were also unsuccessful. Finally we chose to modify the synthesis of a simpler, related tetracycle for the synthesis of arboflorine, developed by Bosch and Passarella. Following their general synthetic strategy we were able to synthesize a key nitrile intermediate to the synthesis of arboflorine. The cyclization of this nitrile was attempted but was not successful under a series of reaction conditions. Chapter 4 describes the structural elucidation of the peroxide IV. A possible mechanistic explanation for the formation of the peroxide is given and this is discussed in the context of relevant literature examples. The formation of the peroxide IV led to our increased interest in the general reactivity of the azepino[4,5-b]indoles and several simple reactions were carried out in the hope of discovering further novel rearrangements.