Reactions of Sydnones with Alkenes

Synthesis of bis‐pyrrole tetra esters and alcohols as novel mimetics of the anticancer mitomycin

“…The bis‐Reissert perchlorate salts 8 prepared as above could be successfully converted to the target bis‐pyrrole tetra esters of general structure 2 by reaction with DMAD presumably via the meso‐ionic species 9 (munchnone imines) [12a, 24] in a 1,3‐dipolar cycloaddition reaction as shown in the general reaction sequence in Scheme . Presumably, the 1,3‐dipolar cycloaddition reaction results in the initial formation of a bicyclic cycloadduct 10 that undergoes cycloreversion by retro‐Diels–Alder reaction to give the pyrrole esters via elimination of the isocyanic acid.…”

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

“…14 The most important chemical reaction of sydnones is 1,3-dipolar cycloaddition with alkynes to give pyrazoles that have numerous applications as pharmaceuticals and agrochemicals. [15][16][17][18][19][20][21] Also, the sydnones served as a key intermediate in the synthesis of the alkaloid withasomnine 22 As a result of their interesting chemistry, biological and physicochemical properties, sydnones have already been the subject of various reviews. 10,23,24 On the other hand, the pyrroloazines, pyrrolo[2,1-a]phthalazines and pyrrolo[2,1-a]isoquinolines have attracted more attention due to their biological [25][26][27][28][29][30] and optical 31,32 properties.…”

1,3-Dipolar Cycloaddition in the Synthesis of Novel Isoxazoline/Pyrazole Derivatives Bearing 1,2,3-Triazoles Moiety

“…Regioselective synthesis of the pyrazole ring remains a significant challenge for organic chemists. Meanwhile, sydnones are easily accessible aromatic compounds and versatile synthetic intermediates with a masked azomethine imine or hydrazine unit . The 1,3‐dipolar cycloaddition reaction with various simple dipolarophiles such as alkynes and alkenes offers a convenient synthetic route for the preparation of pyrazole derivatives , However, less attention has been paid on the 1,3‐dipolar cycloaddition of sydnones with more complex dipolarophiles.…”

“…Meanwhile, sydnones are easily accessible aromatic compounds and versatile synthetic intermediates with a masked azomethine imine or hydrazine unit . The 1,3‐dipolar cycloaddition reaction with various simple dipolarophiles such as alkynes and alkenes offers a convenient synthetic route for the preparation of pyrazole derivatives , However, less attention has been paid on the 1,3‐dipolar cycloaddition of sydnones with more complex dipolarophiles. Recently, literature reported a convenient access to 1,3,4‐trisubstituted pyrazoles by the reaction of sydnones with unsymmetrical acetylenic ketones (dipolarophiles) , but now, we found that replacing acetylenic ketones with unsymmetrical propenones (α,β‐unsaturated ketones) can also afford 1,3,4‐trisubstituted pyrazoles.…”