A study of the reactivity of a tetraphosphadeltacyclene

The selective deselenation of the recently described tetraphosphatetracycle 4a leads to the tetraphosphabishomoprismane 6 in high yield. Triethyl-phos phine is used as a deselenating reagent. A further example for a selective decomposition of 4a is performed by mesitylnitrile oxide (9), yielding the 1,2,4-oxazaphosphole 10. Bromine and iodine furnish tetracyclic rearrangeme nt products 13a,b. Fnally, the applicability of the tetracycle 4a as a liga nd in transition metal chemistry is evaluated by complexation with tungsten (14) and, respectively, irn (15) carbonyl fragments. Side aspects of this article are the first synthesis of 3,5-dimesityl-1,2,4 -selenadiphosphole 2e starting from mesitylphosphaalkyne 1e, aas well as th e first report on a mixed substitution at a cage compound of type 4. (C) 20 01 John Wiley & Sons, Inc.