β Scribed by Ravit Chen; Eli Breuer
No coin nor oath required. For personal study only.
The reaction of diethyl methyl phosphonoacetate (1) with hydroxylamine in NaOH solution resulted in the loss of one of the phosphorus ethyl groups, and yielded monoethylphosphonoacetohydroxamic acid (2) as the major product (79%) and diethylphosphonoacetic acid (3) as the minor product (21%). A series of control experiments were carried out to elucidate the sequence of the reactions leading to 2. When the reaction of 1 with NH~2~OH was carried out in NaHCO~3~ solution, a transient product 4 was also observed, which slowly transformed to 2. Compound 4 was assigned the structure diethylphosphonoacetohydroxamic acid. There was no dealkylation observed at the phosphorus when 1 was reacted with methoxylamine or when Oβmethyl diethylphosphonoacetohydroxamate (7) was placed in alkaline solution. The dealkylation at phosphorus was interpreted in terms of intramolecular nucleophilic catalysis by the hydroxamic OH group attacking the phosphorus in 4, involving cyclic 1,2,5βoxazaphospholidine intermediates. Β© 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:67β71, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10082
π SIMILAR VOLUMES
2-Hydroxyacetophenones undergo upon nitration in acetic acid a substitution of the acyl by nitro group followed by an intramolecular 1,3-acyl shift reminescent of a retro-Fries rearrangement to yield phenyl esters.