1998 organo-phosphorus compounds, isocyclic O,N,S derivatives

organo-phosphorus compounds, isocyclic O,N,S derivativesS 0083

21 - 165Dealkylation of 4-Phosphorylated 5-Alkoxypyrazoles: Easy SyntheticAccess to P-Chloro Ylides. — Alkoxypyrazoles (I) and (XI), bearingbis-dialkylamino- or diphenylphosphino groups, are chlorinated to give highlyunstable chlorophosphonium chlorides which decompose giving ylides (II) and(XII), respectively. These ylides do not react with aromatic aldehydes, butsubstitution of the chlorine atoms easily occurs through Ar–NH, Et2N, NH2,and OH residues. The P-chloro ylides exhibit basic properties. For instance,ylide (IIb) adds hydrogen chloride to furnish the crystalline salt (VIII). —(TOLMACHEV, A. A.; KONOVETS, A. I.; KOSTYUK, A. N.; CHERNEGA,A. N.; PINCHUK, A. M.; Heteroat. Chem. 9 (1998) 1, 41-49; Inst. Org. Chem.,Acad. Sci. Ukr., Kiev 253660, Ukraine; EN)

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1998 organo-phosphorus compounds, isocyclic O,N,S derivatives

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