Phosphorus-nitrogen-sulfur rings

The combination of the monomer units R2PN and NS provides many possibilities for inorganic ring systems containing phosphorus, nitrogen, and two coordinate sulfur. Thus one might an-... 

Similarly the combination of R2PN and NSCl units affords heterocycles containing phosphorus, nitrogen and three coordinate sulfur (e.g. and 5) which may be considered as hybrids of the well known ring systems (R2PN)3 and (NSC1)3. 

Halogens Nitrogen Sulfur Phosphorus Nucleophilic substitution Ring-opening Addition... 

Yamazaki [51] has reviewed a number of stoichiometric cycloaddition reactions at the cobaltacyclopentadiene ring system that lead to a plethora of heterocycles. For example, five- and six-membered heterocycles containing nitrogen, sulfur, selenium, and phosphorus have been made accessible by this route (eq. (20)) [52]. The co-cyclization of substituted alkynes and isocyanates in the presence of a rhodium metallocycle gives 2-pyridones (eq. (21)) [53]. 

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