Synthesis 2007(11): 1697-1701  
DOI: 10.1055/s-2007-966054
PAPER
© Georg Thieme Verlag Stuttgart · New York

Two New Syntheses of a 4-Aminopyrazole: Condensation of an N-Substituted Vinamidinium Salt with a Functionalized Hydrazine

George B. Hill*, Andrew A. Mortlock
Cancer and Infection Research Area, AstraZeneca R & D, Mereside, Alderley Park, Macclesfield, Cheshire, SK10 4TF, UK
Fax: +(44)1625510097; e-Mail: george.b.hill@astrazeneca.com;
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Publikationsverlauf

Received 21 February 2007
Publikationsdatum:
11. Mai 2007 (online)

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Abstract

Two novel syntheses of a key 4-aminopyrazole synthetic building block are described. Both routes avoid the potentially explosive precursors that were used in the previously patented route. A salt of a vinamidinium cation previously used in 5-aminopyrimidine synthesis was condensed with a protected hydrazine salt leading to a 4-aminopyrazole. Buchwald-type amination coupling has also been shown to yield the same compound.