A New and Efficient Synthesis of Pyridazin-3(2H)-ones via 1,3-Dipolar Cycloaddition

First Example of Lewis Acid Catalyzed 3-Substituted 5-Arylidene-1-methyl-2-thiohydantoin Formation

“…Our observations showed that, in general, uncatalyzed reactions give modest to good yields of 40% to 80% with unhindered aldehydes and that sterically hindered aldehydes typically gave very poor results. Similar results (Scheme 2) are found in the literature for other carbonyl compounds including 1,3-dihydroindol-2-one (4, oxindole), 5 a,b-unsaturated ketones, 6,7 3-phenylisoxazol-5-one (5), 8 benzofuran-2(3H)one (6), 9 pyrazol-5-one (7), 10 and 2-phenyl-3-thiazolin-5one (8). 11 The use of catalysts (AlCl 3 , TsOH and KF/alumina) has been reported for other similar substrates, in particular oxindole, with good results for a limited number of examples.…”

Reaction of 2-Benzoyl-1,2-dihydroisoquinoline-1-carbonitrile Tetrafluoroborate with (Z)-2-Arylidene-3(2H)-benzofuranones – Access to Chromenopyrrole Derivatives

“…The regiochemistry of the re-dered than the initial spiro-compound 7. We have observed a similar conversion during the condensation of the same action is similar to that observed [3] [7] [8] for an olefin activated by an electron-withdrawing group, which is always tetrafluoroborate salt with (Z)-and (E)-3-arylidene-3H-benzofuran-2-one [7] . We should mention here the studies of situated at the 3-position of the resulting pyrrole.…”

“…tetrafluoroborate salts of 2-acyl-1,2-dihydroisoquinoline-1-Recently [7] we reported the preparation of 4-aryl-4,5-di carbonitriles (Reissert compounds) exist as equilibrium hydro-5-hydroxy-2-(1-isoquinolinyl)-5-phenylspiro[3H-pyrmixtures of 1؊4, with 4 being the major component role-3,3Ј-(3ЈH)-benzofuran-2Ј-one] and 4-aryl-3-(o-hydroxy-(Scheme 1). According to McEwen [3] , the acid-catalysed phenyl)-2-(1-isoquinolinyl)-5-phenylpyrrole by the reaction condensationϪrearrangement of these salts with an alkene of the tetrafluoroborate salt 4 (Reissert compound) with afford substituted 2-(1-isoquinolinyl)pyrroles 5 (Scheme 1).…”

Application of the anionic homologous Fries‐rearrangement to the synthesis of 3‐alkylbenzofuran‐2(3H)‐ones

“…Accordingly, quenching the metalated amide with Br(CH 2 ) 3 Cl and 4-BrC 6 H 4 CH 2 Br, followed by acidic cyclization of the crude reaction mixtures, led to the recovery of benzofuranones 4ag and 4ah, respectively ( Table 1, entries 8 and 9). [11] The procedure was successfully extended to amides 2b and 2c, thus allowing the synthesis of the alkylated amides 3ba-bb and 3ca-cd, respectively. Acidic cyclization of these crude compounds afforded the corresponding benzofuran-2(3H)-ones, 4ba-bb and 4ca-cd, in satisfactory overall yields (Scheme 2, Table 1, entries 10-15).…”