Sulfonylpyrazole- and pyrazole-directed -selective C-H functionalization/alkenylation and desulfenylative olefination of aryl(sulfonyl)pyrazoles

• Published in: Organic & biomolecular chemistry Vol. 21; no. 41; pp. 831 - 835
• Main Authors: Ahmed, Mukhtar, Mahajan, Shivangani, Kour, Jaspreet, Sawant, Sanghapal D
• Format: Journal Article
• Published: 25.10.2023
• ISSN: 1477-0520; 1477-0539
• DOI: 10.1039/d3ob01262j

ortho -Selective C-H alkenylation of arenes was achieved using sulfonylpyrazoles and pyrazoles as directing groups, favored by a combination of a Pd(OAc) 2 catalyst, Boc-Sar-OH and silver acetate. A wide variety of mono-alkenylated products of aryl-sulfonylpyrazoles and pyrazoles were synthesized with complete site-selectivity under mild reaction conditions. This transformation tolerated several electron-withdrawing and electron-donating groups on the aryl ring and the yields ranged from 52% to 70%, producing highly decorated/valuable alkenylated sulfonylpyrazole and pyrazole derivatives. Amazingly, switching of the oxidant, with the use of AgBF 4 in place of AgOAc, offered cinnamic acid derivatives through de-sulfonylation followed by alkenylation at the same position with good yields in the case of aryl-sulfonylpyrazoles. These kinds of molecules have great biological importance and target predictions indicate that they may serve as potential antifungal and anti-tumor agents. ortho -Selective C-H alkenylation of arenes was achieved using (sulfonyl)pyrazoles as DGs, favored by combination of Pd(OAc) 2 Boc-Sar-OH and silver acetate. Silver tetrafluoroborate gave de-sulfenylative olefinated products on sulfonylpyrazole.