ISSN:
0021-8383
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
α-Substituted Phosphonates. XXXIV. Esterification and N-Formylation of α-Aminomethane-bisphosphonic Acids with TriethylorthoformateIn contrast to simple mono- and bisphosphonic acids esterification of dialkylaminomethanebisphosphonic acids with orthoformate (OAE) proceeds very slowly. Monoalkyl and monoarylaminomethanebisphosphonic acids, respectively react with OAE in constrast to analogous hydroxy compounds more readily primarily by formylating the N-atom and then esterification to formyl aminomethane bisphosphonictetraesters 10. Acetaminomethanephosphonic acid (12) reacts without N-formylation, while the aminomethanebisphosphonic acid (14) reacted to give a mixture of mono- and bis-formylated products 15 and 16. By acidic hydrolysis of 10 the ester- and formylgroups are splitt off, while the ester group can selectively be removed by reaction with Me3SiBr/H2O. - As shown by 1H-, 13C- and 31P-n.m.r. spectroscopy the phosphorylated formamides 10 exists in two rotameres, the ratio depending on the solvent. The n.m.r. signals could be correlated to E-resp. Z-form undoubtedly by using shift-agents or the benzene-diluting technique. A rotational barrier of 22,8 kcal for 10c could be calculated.
Additional Material:
4 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/prac.19793210303
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