1,3-Dipolar cycloaddition between acetylenic dipolarophiles and sydnone-N-ylides as bis(1,3-dipoles)

Sydnone C-4 heteroarylation with an indolizine ring via Chichibabin indolizine synthesis

“…The formation of cycloadducts 12 implies in the first step the generation of pyridinium N -ylides under the action of 1,2-epoxybutane. The mechanism for the transformation of N -heteroaromatic salts into the corresponding N -ylides with epoxides was reported recently [5,17–18]. The next step represents a 1,3-dipolar cycloaddition of the bis(1,3-dipoles) 10 with formation of dihydro-indolizines 11 which, under the reaction conditions, are dehydrogenated to the final products 12a – c with yields in the range of 41–52%.…”

“…These salts were obtained in good yields by heating pyridines 6a–d with 4-(bromoacetyl)-3-phenylsydnone ( 7 , Scheme 1) in refluxing acetone [5]. The obtained pyridinium salts 8 were used in the next step without further purification.…”

“…Recently, we obtained, by 1,3-dipolar cycloaddition reactions of sydnone-ylides as bis(1,3-dipoles) with activated acetylenes, the hybrid structures 1 containing a pyrroloazine (pyrroloisoquinoline or pyrrolophthalazine) connected to the sydnone ring through a keto group [5]. As a result, it was of interest to prepare analogous compounds containing a pyrroloazine directly attached to the C-4 position of a sydnone ring.…”

Synthesis of 1-(2-Fluorophenyl)pyrazoles by 1,3-Dipolar Cycloaddition of the Corresponding Sydnones

“…The 1,3-dipolar cycloadditions reactions [ 1 ], also known as “Huisgen reactions” [ 2 ], involving 1,3-dipoles from the class of N -ylides [ 3 , 4 , 5 , 6 ], mesoionic compounds such as munchnones [ 7 , 8 ] and sydnones [ 9 , 10 ] and many others [ 11 , 12 ], have been intensively studied in obtaining a wide range of five membered heterocycles ( Figure 1 ) [ 13 ].…”

Introducing chirality in halogenated 3-arylsydnones and their corresponding 1-arylpyrazoles obtained by 1,3-dipolar cycloaddition

“…[6][7][8][9][10][11] Sydnones 12,13 in particular, have been employed as 1,3-dipoles in obtaining N-arylpyrazoles by 1,3-dipolar cycloaddition reaction. [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] N-Arylpyrazole derivatives have been shown to possess antithrombotic, 29 anticancer, 30 parathyroid dysfunction, 31 anti-biolm, 32 and antipain 33 activity which makes them valuable targets for the pharmaceutical eld.…”