P-Stereogenic Heterocycles

The compounds of this class are easy to prepare and are often obtained in high yields and optical purities. Indeed, they probably constitute the easiest entry to optically pure P-stereogenic compounds. Another advantage is that they frequently show marked stability towards moisture and air, in contrast to classic phosphines. 

They deserve a chapter on their own for at least three reasons. Firstly, they have been heavily used to study the complicated stereochemistry of substitution reactions at the phosphorus atom. This can be explained by the restriction of rearrangements that occurs when a P atom is placed in a cycle, although it is often found that in cyclic compounds the stereochemical course of the substitution is different to that of their acyclic counterparts. 

Thirdly, oxazaphospholidines derived from ephedrine are the starting point for one of the principal methods to prepare enantiopure P-stereogenic phosphines, discussed in Chapter 4.  

It would be impossible to give a comprehensive account of all the reported hetereobifunctional P-stereogenic heterocycles in a chapter of practical size. 

P-Stereogenic Ligands in Enantioselective Catalysis By Amald Grabulosa Arnald Grabulosa 2011 

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Many other heterobifunctional chiral auxiliaries have also been employed to alford P-stereogenic heterocycles. Some of them are discussed here. 

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