Resumen de Stereoselective synthesis of polyfunctionalized cyclobutane scaffolds
The present thesis is aimed toward the stereoselective synthesis of trisubstituted cyclobutane compounds 6 and 10 which could be used as versatil building blocks to prepare different functionalyzed cyclobutane nucleoside analogues. We have focused on two methodologies directed to the synthesis of 6 and 10; an intramolecular [2+2] photocycloaddition and a Zr-mediated ring contraction reaction, respectively.
In project 1, we have prepared several dienes and established the best reaction conditions to perform intramolecular [2+2] photocycloadditions (acetonitrile, quartz and -78 °C). Two cyclobutane intermediates 4 and 5 were obtained in good yields. The subsequent cleavage of the linker and lactone opening step on cyclobutane 4 led to the target trisubstituted cyclobutane 6.
The second project is focused on the development of a new stereoselective route to the cyclobutane building block 10 by means of a zirconocene-mediated reaction. The key 4-vinylfuranoside intermediates 8, which bear different substitutes at C-3, were synthesized through two different strategies starting from 1 and 7, respectively. The initial study on zirconocene-mediated reaction of 8a has been carried out.
