| Title:  Seyferth-Gilbert Reagent CAS Registry Number:  27491-70-9 CAS Name:  (Diazomethyl)phosphonic acid dimethyl ester Additional Names:  dimethyl diazomethylphosphonate Molecular Formula:  C3H7N2O3P Molecular Weight:  150.07 Percent Composition:  C 24.01%, H 4.70%, N 18.67%, O 31.98%, P 20.64% Literature References:  Divalent carbon transfer reagent.  Prepn:  D. Seyferth, R. S. Marmor, Tetrahedron Lett. 11, 2493 (1970); and applications in organophosphorus syntheses:  D. Seyferth et al., J. Org. Chem. 36, 1379 (1971).  Reactions with aldehydes and aryl ketones to form alkynes:  J. C. Gilbert, U. Weerasooriya, ibid. 47, 1837 (1982).  Improved prepn:  D. G. Brown et al., ibid. 61, 2540 (1996). Properties:  Distillable yellow liquid, bp0.42 59°.  nD25 1.4585. Boiling point:  bp0.42 59° Index of refraction:  nD25 1.4585 Use:  Reagent for one-carbon homologation of aldehydes and ketones to alkynes.  |