Reactions of Pyridine Analogues of Aza-ortho-xylylenes Generated from 1,3-Dialkylpyridosultams

Electron ionization‐induced fragmentation of 3‐cyclopropanospiro and 3‐cyclobutanospiro derivatives of Benzo‐ and pyridosultams

“…Analogous transformations were observed for 1-methyl-3-cyclopropanospiropyridosultam 8b. 2 Three other pyrolysis products with RT = 3.26, 3.46 and 3.78 min show mass spectra almost identical with that of 1,3-dimethylindole. There are insufficient data to establish the structures of these products, but structure 16 or 1methyldihydroquinolines such as 18 and 19 are possible.…”

Electron ionization‐induced fragmentation of 3‐cyclopropanospiro and 3‐cyclobutanospiro derivatives of Benzo‐ and pyridosultams

“…Analogous transformations were observed for 1-methyl-3-cyclopropanospiropyridosultam 8b. 2 Three other pyrolysis products with RT = 3.26, 3.46 and 3.78 min show mass spectra almost identical with that of 1,3-dimethylindole. There are insufficient data to establish the structures of these products, but structure 16 or 1methyldihydroquinolines such as 18 and 19 are possible.…”

Acid-Mediated Domino Cyclization of ortho-Formyl Cinnamate Esters: Synthesis of Substituted Indene/Indane Esters and Indeno[a]indenones

“…Also, [1,5-H] shift in cyclopentadienes or their structural equivalents could be feasible under acidic conditions and generate the corresponding double bond isomerization products. Fortunately, we were able to come across such similar [1,5-H] shifts either under metal-catalyzed conditions , or heat-promoted conditions. − …”

“…Therefore, based on the above additional experiments (Scheme a,b), X-ray analysis of compound 4′dg , previous literature reports − for the double bond isomerization {i.e., [1,5-H] shift}, including our previous work, a possible reaction mechanism was drawn for the formation of compounds “ 4dg+4′dg ” and “ 4fg+4′fg ”, as outlined in Scheme . The formation of the intermediate indenol-ester I a from acrylates 2 in the presene of acid via intramolecular cyclization pathway as already shown in those mentioned above plausible general reaction mechanism [i.e., for the formation of 4ag / 5ag / 7ag starting from cinnamate ester 2a and external arene 3g (Scheme )], subsequently, in the presence of an acid, the hydroxyl group of the intermediate I a gets protonated and forms the intermediate Q .…”

Reactions of Pyridine Analogues of Aza-o-xylylenes Generated from 1,3-Dihydroisothiazolo[4,3-b]pyridine 2,2-Dioxides (Pyridosultams) − Formation of 2:1 Adducts withN-Phenylmaleimide

“…[27] When equimolar amounts of pyridosultam 11 and N-phenylmaleimide (21) were heated in boiling 1,2,4-trichlorobenzene (215°C), the extrusion of SO 2 proceeded readily. After 30 min, the starting sultam 11 had completely disappeared, but the expected 8a,9-dihydro-5H-pyrrolo[3,4-b]-1,5-naphthyridine-6,8(5aH,7H)-dione (23) had been formed only in low yield.…”

“…Pyridosultams 11؊16 were obtained according to the procedure described earlier. [27] High-pressure quaternization of compound 48 was performed in a piston-type apparatus designed and constructed in the Institute of Physical Chemistry (Warsaw). For a general description see ref.…”

Electron ionization‐induced fragmentation of 3‐cyclopropanospiro and 3‐cyclobutanospiro derivatives of Benzo‐ and pyridosultams

“…Analogous transformations were observed for 1-methyl-3-cyclopropanospiropyridosultam 8b. 2 Three other pyrolysis products with RT = 3.26, 3.46 and 3.78 min show mass spectra almost identical with that of 1,3-dimethylindole. There are insufficient data to establish the structures of these products, but structure 16 or 1methyldihydroquinolines such as 18 and 19 are possible.…”

Acid-Mediated Domino Cyclization of ortho-Formyl Cinnamate Esters: Synthesis of Substituted Indene/Indane Esters and Indeno[a]indenones

“…Also, [1,5-H] shift in cyclopentadienes or their structural equivalents could be feasible under acidic conditions and generate the corresponding double bond isomerization products. Fortunately, we were able to come across such similar [1,5-H] shifts either under metal-catalyzed conditions , or heat-promoted conditions. − …”

“…Therefore, based on the above additional experiments (Scheme a,b), X-ray analysis of compound 4′dg , previous literature reports − for the double bond isomerization {i.e., [1,5-H] shift}, including our previous work, a possible reaction mechanism was drawn for the formation of compounds “ 4dg+4′dg ” and “ 4fg+4′fg ”, as outlined in Scheme . The formation of the intermediate indenol-ester I a from acrylates 2 in the presene of acid via intramolecular cyclization pathway as already shown in those mentioned above plausible general reaction mechanism [i.e., for the formation of 4ag / 5ag / 7ag starting from cinnamate ester 2a and external arene 3g (Scheme )], subsequently, in the presence of an acid, the hydroxyl group of the intermediate I a gets protonated and forms the intermediate Q .…”

Reactions of Pyridine Analogues of Aza-o-xylylenes Generated from 1,3-Dihydroisothiazolo[4,3-b]pyridine 2,2-Dioxides (Pyridosultams) − Formation of 2:1 Adducts withN-Phenylmaleimide

“…[27] When equimolar amounts of pyridosultam 11 and N-phenylmaleimide (21) were heated in boiling 1,2,4-trichlorobenzene (215°C), the extrusion of SO 2 proceeded readily. After 30 min, the starting sultam 11 had completely disappeared, but the expected 8a,9-dihydro-5H-pyrrolo[3,4-b]-1,5-naphthyridine-6,8(5aH,7H)-dione (23) had been formed only in low yield.…”

“…Pyridosultams 11؊16 were obtained according to the procedure described earlier. [27] High-pressure quaternization of compound 48 was performed in a piston-type apparatus designed and constructed in the Institute of Physical Chemistry (Warsaw). For a general description see ref.…”

Electron ionization‐induced fragmentation of 3‐cyclopropanospiro and 3‐cyclobutanospiro derivatives of Benzo‐ and pyridosultams

“…Analogous transformations were observed for 1-methyl-3-cyclopropanospiropyridosultam 8b. 2 Three other pyrolysis products with RT = 3.26, 3.46 and 3.78 min show mass spectra almost identical with that of 1,3-dimethylindole. There are insufficient data to establish the structures of these products, but structure 16 or 1methyldihydroquinolines such as 18 and 19 are possible.…”

Acid-Mediated Domino Cyclization of ortho-Formyl Cinnamate Esters: Synthesis of Substituted Indene/Indane Esters and Indeno[a]indenones

“…Also, [1,5-H] shift in cyclopentadienes or their structural equivalents could be feasible under acidic conditions and generate the corresponding double bond isomerization products. Fortunately, we were able to come across such similar [1,5-H] shifts either under metal-catalyzed conditions , or heat-promoted conditions. − …”

“…Therefore, based on the above additional experiments (Scheme a,b), X-ray analysis of compound 4′dg , previous literature reports − for the double bond isomerization {i.e., [1,5-H] shift}, including our previous work, a possible reaction mechanism was drawn for the formation of compounds “ 4dg+4′dg ” and “ 4fg+4′fg ”, as outlined in Scheme . The formation of the intermediate indenol-ester I a from acrylates 2 in the presene of acid via intramolecular cyclization pathway as already shown in those mentioned above plausible general reaction mechanism [i.e., for the formation of 4ag / 5ag / 7ag starting from cinnamate ester 2a and external arene 3g (Scheme )], subsequently, in the presence of an acid, the hydroxyl group of the intermediate I a gets protonated and forms the intermediate Q .…”

Reactions of Pyridine Analogues of Aza-o-xylylenes Generated from 1,3-Dihydroisothiazolo[4,3-b]pyridine 2,2-Dioxides (Pyridosultams) − Formation of 2:1 Adducts withN-Phenylmaleimide

“…[27] When equimolar amounts of pyridosultam 11 and N-phenylmaleimide (21) were heated in boiling 1,2,4-trichlorobenzene (215°C), the extrusion of SO 2 proceeded readily. After 30 min, the starting sultam 11 had completely disappeared, but the expected 8a,9-dihydro-5H-pyrrolo[3,4-b]-1,5-naphthyridine-6,8(5aH,7H)-dione (23) had been formed only in low yield.…”

“…Pyridosultams 11؊16 were obtained according to the procedure described earlier. [27] High-pressure quaternization of compound 48 was performed in a piston-type apparatus designed and constructed in the Institute of Physical Chemistry (Warsaw). For a general description see ref.…”