Ligand-Promoted Alkynylation of Aryl Ketones: A Practical Tool for Structural Diversity in Drugs and Natural Products was written by Xu, Hui;Ma, Biao;Fu, Zunyun;Li, Han-Yuan;Wang, Xing;Wang, Zhen-Yu;Li, Ling-Jun;Cheng, Tai-Jin;Zheng, Mingyue;Dai, Hui-Xiong. And the article was included in ACS Catalysis in 2021.Name: Benzothiazole-5-carboxylic acid This article mentions the following:
A palladium-catalyzed ligand-promoted alkynation of unstrained aryl ketones RC(O)R1 (R = naphthalen-2-yl, 1-benzothiophen-5-yl, 4-(2H-1,2,3-triazol-2-yl)benzen-1-yl, etc.; R1 = Me, n-Pr, Ph, etc.) have been reported. The protocol allows the alkynation to be carried out in a one-pot procedure with broad functional-group tolerance and substrate scope for the synthesis of aryl-/terminal alkynes RCCR2 (R2 = 2-fluorophenyl, naphthalen-2-yl, thiophen-2-yl, etc.) and RCCH. The potential applications of this protocol in drug discovery and chem. biol. are further demonstrated by late-stage diversification of a number of pharmaceuticals and natural products e.g., I. More importantly, two different biol. important fragments R3CCR4 (R = 3-methoxy-4-([(2S,3R,4S,5R,6R)-3,4,5-tris(acetyloxy)-6-[(acetyloxy)methyl]oxan-2-yl]oxy)benzen-1-yl, 6-[3-(adamantan-1-yl)-4-methoxyphenyl]naphthalen-2-yl; R4 = 4-(dipropylsulfamoyl)phenyl) derived from a pharmaceutical and natural product could be connected by the consecutive alkynation of ketones CH3(CH2)2C(O)R4. Distinct from aryl halides in conventional Sonogashira reactions, the protocol provides a practical tool for the 1,2-bifunctionalization of aryl ketone (1-[(17β)-17-(acetyloxy)estra-1,3,5(10)-trien-2-yl]ethanone) by merging ketone-directed ortho-C-H activation with ligand-promoted ipso-Ar-C(O) alkynation. In the experiment, the researchers used many compounds, for example, Benzothiazole-5-carboxylic acid (cas: 68867-17-4Name: Benzothiazole-5-carboxylic acid).
Benzothiazole-5-carboxylic acid (cas: 68867-17-4) belongs to thiazole derivatives. The thiazole ring has been identified as a central feature of numerous natural products, perhaps the most famous example of which is epothilone. The pyridine-type nitrogen in the thiazole ring deactivates the ring for electrophilic substitution reactions, which is further reduced in acid due to protonation of the thiazole ring.Name: Benzothiazole-5-carboxylic acid
Referemce:
Thiazole | C3H3NS – PubChem,
Thiazole | chemical compound | Britannica