P. Losier et al., FROM A HETEROCYCLE THROUGH A HETERO(SPIRO)CYCLE TO A GENUINE HETEROCYCLE, Phosphorus, sulfur and silicon and the related elements, 93(1-4), 1994, pp. 463-464
A ''Genuine Heterocycle'' containing a PNAlS framework is obtained fro
m a heterocyclic phosphenium species with a novel heterobis(spiro)tric
ycle as an isolable intermediate.