Taxane Diterpene Synthesis Studies. Part 2: Towards Taxinine-Enantiospecific Construction of an AB-ring Substructure Incorporating both Quaternary Carbon Centres and Attempts to Annulate the C-ring

Banwell, MartinMcLeod, MalcolmRiches, Andrew G2015-12-132015-12-130004-9425http://hdl.handle.net/1885/78445In connection with efforts to develop an efficient total synthesis of the biologically active natural product taxinine 1, the enzymatically-derived and monochiral cis-1,2-dihydrocatechol 7 was converted, over several steps including a Diels-Alder cycloaddition reaction, into the bicyclo[2.2.2]octan-2-one 18. Reaction of the last compound with the organocerium reagent 22 afforded the 1,5-diene 23 which engaged in an anionic oxy-Cope rearrangement reaction to give, after C-methylation of the product enolate 25, bicyclo[5.3.1]undecenone 27 embodying the AB-ring system of target 1. Two methods for allylic oxidation of such products were developed and several unsuccessful attempts to effect a cyclization reaction so as to establish the taxane C-ring are described.Keywords: Addition reactions; Carbon; Cerium compounds; Crystal structure; Crystalline materials; Enzymes; Olefins; Oxidation; Synthesis (chemical); Diels Alder cycloaddition reaction; Dihydrocatechol; Methylation; Organocerium reagent; Taxane diterpene; Taxinine;Taxane Diterpene Synthesis Studies. Part 2: Towards Taxinine-Enantiospecific Construction of an AB-ring Substructure Incorporating both Quaternary Carbon Centres and Attempts to Annulate the C-ring200410.1071/CH031612015-12-11