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A novel P-cage type of the title compounds were discussed in terms of X-Ray analyses and molecular orbital calculations. In solid state, trans-4-phenyl-4-phosphatetracyclo[3.3.0 2,8 .0 3,6 ]octane 4-oxide (trans-5) is much more strained and asymmetric, whereas cis-6-phenyl-6-phosphapentacyclo[6.3,1.0 2,4 .0 3,7 .0 5,10 ]dodecane 6-oxides (cis-4) is less strained and highly symmetric. Molecular mechanics, semi-empirical, ab initio, and DFT calculations were used to estimate the relative energy of cis-4, trans-4, cis-5, and trans-5.

Cycloaddition reactions of 6-cyanobenz[a]indolizines with activated alkynes such as dimethyl acetylenedicarboxylate, diacetylacetylene, methyl propiolate, methyl trimethylsilylpropiolate, methyl phenylpropiolate, and 4-phenyl-3-butyn-2-one were investigated.

Title compounds were prepared through high pressure S N Ar reactions (0.8 GPa, 100 ° C) of homopiperazine with five- and six-membered heteroatomic halides, the yields being good to excellent when the halides are activated by electronic effects