Tetraphosphatricyclo[4.2.0.0~(2,5)]octadienes; New Phosphaalkyne Cyclotetramers Derived from lambda~3 rho~2-Diphosphetes

摘要

In the cyclooligomenzation of alkynes there is a special interest in their cyclotetramers as also is the case in the series of phos-phaalkynes (RCsP). Following the original thermal cyclote-tramerization of /BuC=P with low selectivity to the tetraphos-phacubane 1, specific high-yield syntheses enable a detailed study to be made of the reactivity of this pentacycle. Utilizing a stepwise route, the polycyclic isomers 2 and 3 containing phosphaalkene units are now accessible which, on heating, quantitatively transform to the more thermodynami-cally stabie compound 4, which only contains lambda~3 rho~2-phosphorus atoms.