1,3,2-Diazaphospholidine ring

Treatment of the carbanions from P-alkyl analogues of compound 336 with 2,4,6-tri-isopropylbenzenesulphonyl azide yields the azides (397) diastereoselectively acidolytic removal of the 1,3,2-diazaphospholidine ring and catalytic reduction of the azido group affords (l-aminoalkyl)phosphonic acids of known chirality. ... 

Scheme 25). l-Oxo-2,8-diphenyl-2,5,8 triaza-1 X -phosphabicyclo[3.3.0]octane (68) formed by acid catalysis of the bicyclic phosphoric triamide (67) has been found to isomerize via a new type of rearrangement to yield the ring contracted 3-[2-(phenylamino)ethyl]-2-oxo-2-ethoxy-l-phenyl-l,3,2 A, -diazaphospholidine (69). The rearrangement has been explained in terms of intramolecular 1,5-nucleophilic attack... 

X-ray diffraction analysis of the borane adduct of 2 (R = Ar = Ph, Scheme 3.1) revealed the P-bonded extracyclic phenyl group to be in the traits position to the pyrrolidine ring, forcing the phosphorus atom to adopt R as the absolute configuration in order to minimise steric effects. Most of the diazaphospholidines prepared by route B are listed in Table 3.2. 

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