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Title: Rhodium(I)-catalysed carbocyclisation reactions of alkylidenecyclopropane tethered with dienes for the construction of cis-fused 5,5-bicyclic ring and 5,7-bicyclic ring systems : synthetic study towards the total synthesis of zaluzanin E
Author: Ojo, Oluwarotimi
ISNI:       0000 0004 6057 7581
Awarding Body: University of Liverpool
Current Institution: University of Liverpool
Date of Award: 2014
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The construction of 5,5-bicyclic and 5,7-bicyclic systems, specifically, the cis-fused type, has become an increasingly important and growing area of research. Numerous synthetic methodologies have been developed towards the preparation of these attractive structural motifs, due to their presence in both structurally challenging and biologically important natural products. In our effort to contribute to the vast arsenal of synthetic approaches which are utilised for constructing these bicyclic systems, we herein report a highly selective synthesis of cis-fused 5,5-bicyclic and cis-fused 5,7-bicyclic systems via rhodium(I)-catalysed [3+2] and [4+3] carbocyclisation reactions of alkylidenecyclopropane and dienes, respectively. A novel diastereoselective version of these reactions was also developed for the synthesis of bicyclic systems with three stereogenic centres. The scope and limitation of these transformations was examined and it was utilised as a key strategy for the synthesis of 1-epi-dictamnol, a natural product which possesses a tertiary alcohol. Synthetic Studies Towards the Total Synthesis of Zaluzanin E The rhodium(I)-catalysed [4+3] carbocyclisation reaction was employed for the diastereoselective construction of a cis-fused 5,7-bicyclic ring with four stereogenic centres. Further synthetic manipulation of the 5,7-bicyclic ring provides an advanced late stage intermediate, a 5,7,5-tricyclic ring, towards the first total synthesis of zaluzanin E. This intermediate can also be used as an entry point to assemble other guaianolide natural products.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral