Rhodium(III)‐Catalyzed Alkynylation of 4‐Arylphthalazin‐1(2H)‐one Scaffolds via C‐H Bond Activation

Abstract

Selective C–H bond alkynylation toward modular access to material and pharmaceutical molecules is of great desire in modern organic synthesis. Disclosed herein is rhodium(III)‐catalyzed selective C–H bond mono‐/bialkynylation of 4‐aryl phthalazin‐1(2H)‐one was developed. The silver salt AgSbF6 are demonstrated to play a vital role in promoting the bialkynylation reactions. The present alkynylation strategy is simple, efficient, and features high functional group tolerance and broad substrate scope under an air atmosphere. Additionally, 6‐aryl pyridazin‐3(2H)‐one scaffold is amenable to the selective monoalkynylation and sequential bialkynylation, respectively.

Transition‐metal‐free Cyclization of Mucohalic Acids with Sulfonyl Hydrazides: An Approach to Pyridazin‐3(2H)‐ones

“…When changing the single solvent system into a mixture of acetonitrile/toluene (1/1, v/v) as the solvent (entries 13 vs 6, 12), the yield can be increased slightly even at the same reaction temperature of 85 °C. For the mixture of acetonitrile/ toluene (1/1, v/v), its various reaction temperature was further screened (entries [13][14][15]. Obviously, when the temperature 95 °C is optimal for the corresponding yield is increased substantially to 95 % (entry 14), while there is a marked decrease at the higher temperature (entry 15).…”

“…[9][10][11][12] Among the derivatives of pyridazine ring, pyridazin-3(2H)-ones are one of the most representative subtypes of this heterocyclic family, because the structural unit of pyridazin-3(2H)-one is widespread in many drugs, such as, Azelastine (antihistamine allergy), Emorfazone (anti-inflammatory analgesic), and Lynparza (anticancer), which are shown as Figure 1a. [13][14][15] Additionally, vast numbers of pesticides are also pyridazin-3(2H)-one derivatives, e. g., Diclomezine, Flufenpyr and Pyridaben (Figure 1b). [16][17][18][19] Due to the existence of the multiple reaction sites, sulfonyl hydrazides have been widely used as synthons or reagents in the preparation of pharmaceutical active compounds and organic methodology.…”

“…Pyridazine ring is a fundamental building block existing in numerous bioactive compounds, [1–4] though the compounds containing pyridazine ring also have a wide range application in the field of advanced materials [5–8] and fluorescence sensors [9–12] . Among the derivatives of pyridazine ring, pyridazin‐3(2 H )‐ones are one of the most representative subtypes of this heterocyclic family, because the structural unit of pyridazin‐3(2 H) ‐one is widespread in many drugs, such as, Azelastine (antihistamine allergy), Emorfazone (anti‐inflammatory analgesic), and Lynparza (anticancer), which are shown as Figure 1a [13–15] . Additionally, vast numbers of pesticides are also pyridazin‐3(2 H )‐one derivatives, e. g., Diclomezine, Flufenpyr and Pyridaben (Figure 1b).…”