Telescoped Flow Process for the Syntheses of N-Aryl Pyrazoles

Autor:	Cheryl Myers Hayward, Brian T. O’Neil, Yanqiao Xiang, John VanAlsten, Daniel W. Widlicka, John C. Murray, Pfisterer David Michael, Steven J. Boucher, Joseph Michael Young, Lacey Samp, Bryan Li, John C. Lucas
Rok vydání:	2012
Předmět:	chemistry.chemical_classification Aryl Organic Chemistry Hydrazine chemistry.chemical_element Salt (chemistry) Ether Pyrazole Chloride chemistry.chemical_compound Aniline chemistry medicine Organic chemistry Physical and Theoretical Chemistry Tin medicine.drug
Zdroj:	Organic Process Research & Development. 16:2031-2035
ISSN:	1520-586X 1083-6160
Popis:	N-Aryl pyrazoles were prepared from anilines in a three step telescoped approach. An aniline was diazotized to give the diazonium fluoroborate, followed by reduction with tin(II) chloride to give the corresponding hydrazine, which in turn reacted with a ketoenamine to give the N-aryl pyrazole. The deprotection of the methyl ether was accomplished with PhBCl2 to give the final product. The continuous flow methodology was used to minimize accumulation of the highly energetic and potentially explosive diazonium salt and hydrazine intermediates to enable the safe scale-up of N-aryl pyrazoles. The heterogeneous reaction mixture was successfully handled in both lab scale and production scale. A continuous extraction was employed to remove organic impurities from the diazotization step, which eliminated the need for chromatography in the purification of the final N-aryl pyrazole.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::68759d901664a19633cf8684b87f2982 https://doi.org/10.1021/op300209p Zobrazit plný text záznamu