Cyclic oxaza compound

Kobayashi, S. and T. Saegusa, Cyclic 1,3-Oxaza Compounds, Chap. 11 in Ring-Opening Polymerization, Vol. 2, K. J. Ivin, and T. Saegusa, eds., Elsevier, London, 1984. 

New synthetic pathways for the preparation of chiral cyclic oxaza- and diaza-phosphoramidates suitable for use in asymmetric chemistry were studied with respect to the imide-amide rearrangement of cyclic phosphorimidates (Scheme 23). New types of oligomeric organophosphorus compounds (112), formed by a novel ring opening polymerisation, have been identified. These compounds are stable intermediates in the imide-amide rearrangement. 

All cyclic 1,3-oxaza compounds, depicted in Figure 4, are able to give ring-opening reactions and are, as a consequence, in potential all chain extender moieties. Despite all these options, only bisoxazines (1), bisoxazolines (2), and bisoxazolinones (3) are frequently described as chain extenders. 

Cyclic 1,3-oxaza compounds as potential chain extension moieties (depicts only half of the compounds). ... 

Cyclic monomers that have been polymerized via ring-opening encompass a variety of structures, such as alkanes, alkenes, compounds containing heteroatoms in the ring oxygen [ethers, acetals, esters (lactones, lactides, and carbonates), and anhydrides], sulfur (polysulfur, sulfides and polysulfides), nitrogen [amines, amides (lactames), imides, N-carboxyanhydrides and 1,3-oxaza derivatives], phosphorus (phosphates, phosphonates, phosphites, phosphines and phosphazenes), or silicon (siloxanes, silaethers, carbosilanes and silanes). For the majority of these monomers, convenient polymerization conditions have been elaborated, that result in the controlled synthesis of the corresponding polymers [1-13]. 

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