Approaches to cyclobutane containing cage compounds

The aim of this research has been in devising new approaches to cage compounds involving the [2+2] cycloaddition. A major part of this work was directed towards the synthesis of functionalised [4]peristylane (197) as shown below. 4,5-Bis(2-methoxyethane)-1,3-dioxol-2-one (252) was synthesised as a precursor to intermolecular photodimerisation. However, when irradiating 252 no dimers could be isolated. An intramolecular approach was also considered and to this end (Z)4,6,9,11-tetrahydrocyclodeca-1,3-dioxole-2,5,10-trione (308) was synthesised. As anticipated, irradiation of 308 gave the intermediate cis-trans isomerised product 309. Nevertheless, further irradiation of 309 did not give the desired cyclobutane adduct 310. Another area of research has been intermolecular cross dimerisations. Irradiation of vinylene carbonate (41) and maleic anhydride (48) gave a 1:1 mixture of cis-syn-cis and cis-anti-cis cross dimers 341 and 342. The irradiation of vinylene carbonate 41 and 1,3-diacetyl-1,3-dihydro2H-imidazol-2-one (29) gave a single cross dimer 357 which was assigned the cis-anti-cis stereochemistry. These cyclisation products could potentially be used as intermediates en route to hetero-cage compounds. (author)