Download PDF
Synthesis 2009(6): 921-928  
DOI: 10.1055/s-0028-1083357
PAPER
© Georg Thieme Verlag Stuttgart ˙ New York

Copper-Catalyzed Selective S-Arylation of 1,2-Bis(o-amino-1H-pyrazolyl) Disulfides with Arylboronic Acids

Pei-Song Luoa, Feng Wangb, Jin-Heng Li*a,b, Ri-Yuan Tanga, Ping Zhong*a
a College of Chemistry and Materials Science, Wenzhou University, Wenzhou 325035, P. R. of China
b Key Laboratory of Chemical Biology & Traditional Chinese Medicine Research (Ministry of Education), Hunan Normal University, Changsha 410081, P. R. of China
Fax: +86(731)8872101; e-Mail: jhli@hunnu.edu.cn;
Further Information

Publication History

Received 14 October 2008
Publication Date:
11 February 2009 (online)

    Permissions and Reprints All articles of this category

Abstract

Copper-catalyzed oxidative S-arylation of 1,2-bis(o-amino-1H-pyrazolyl) disulfides with arylboronic acids for the synthesis of (o-amino-1H-pyrazolyl)aryl sulfides has been developed in the presence of CuI, 1,10-phenanthroline, and O2. A variety of dipyrazolyl disulfides bearing free NH2 groups underwent the reaction with arylboronic acids efficiently to selectively afford the corresponding S-arylation products in moderate to excellent yield. It is noteworthy that amino groups are tolerated well, and a series of fipronil analogues are prepared.

Key words

copper - 1,10-phenanthroline - S-arylation - 1,2-bis(o-amino-1H-pyrazolyl) disulfides - arylboronic acid - (o-amino-1H-pyrazolyl)aryl sulfide

9

Oxygen may play at least three roles in the present reaction including: (1) promoting the generation of Cu(SR)Ar from Cu(I)SR and ArB(OH)2 to accelerate the catalytic cycle, (2) regenerating the active Cu(I) species from the Cu(SR)Ar intermediate, and (3) restraining N-arylations of organoboronic acids with amines. See refs. 6 and 8.