期刊
SYNTHESIS-STUTTGART
卷 -, 期 -, 页码 -出版社
GEORG THIEME VERLAG KG
DOI: 10.1055/a-2063-0303
关键词
site-selective cross-coupling reaction; pyrazolo[1; 5-a ]pyrimidine; Suzuki-Miyaura reaction; arylation; alkynylation; amination
A range of new disubstituted pyrazolo[1,5-a]pyrimidine derivatives were synthesized via sequential site-selective cross-coupling reactions of ethyl 2,6-dibromopyrazolo[1,5-a]pyrimidine-3-carboxylate. After careful optimization, the regiocontrolled Suzuki-Miyaura reaction exhibited excellent selectivity at position C6. The monobrominated compounds were further transformed through arylation, alkynylation, or amination, leading to a novel series of ethyl 2,6-disubstituted pyrazolo[1,5-a]pyrimidine-3-carboxylates. This approach provides an efficient regioselective method for diversification of the chemically and biologically interesting pyrazolo[1,5-a]pyrimidine heterocycle at positions C2 and C6.
A variety of novel disubstituted pyrazolo[1,5-a]pyrimidine derivatives have been prepared via sequential site-selective cross -coupling reactions of ethyl 2,6-dibromopyrazolo[1,5-a]pyrimidine-3-car-boxylate. The regiocontrolled Suzuki-Miyaura reaction proceeded with excellent selectivity in favor of position C6 after careful optimization of the cross-coupling conditions. The monobrominated compounds, obtained on a large scale, were subjected to a second arylation, alkynylation or amination, leading to a new series of ethyl 2,6-disubstituted pyrazolo[1,5-a]pyrimidine-3-carboxylates. These results constitute an efficient regioselective approach for diversification of the chemically and biologically interesting pyrazolo[1,5-a]pyrimidine heterocycle at C2 and C6 positions.
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