Organophosphorus compounds; 141. Phosphorus-containing cage compounds fromthe reaction of 7,8-dichlorocycloocta-1,3,5-triene with tert-butylphosphaacetylene and subsequent chemistry

tert-Butylphosphaacetylene (1) reacts at 120 degrees C with the bicyclic fo rm of cis-7,8-dichlorocycloocta-1,3,5-triene (11) in a Dials-Alder reaction to furnish the tricyclic product 12, whose constitution was confirmed by s ingle crystal structure analysis of the corresponding eta(1) -pentacarbonyl tungsten complex 14. Compound 12 possesses a sterically fixed 1,4-diene sys tem and fulfills the structural prerequisite for homo-Diels-Alder reactions , which can be realized with the electron-poor acetylenes 15 as well as the phosphaacetylene 1 (--> 16, 20). Furthermore, the polycyclic systems 16 ca n be oxidized and complexed at the phosphorus atom (--> 18, 19).