Synthesis of 1,4-dithiocins. 1,6-Benzodithiocin

Coffen, David L.; Poon, Y. C.; Lee, M. L.

doi:10.1021/ja00747a068

Cited by 29 publications

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“…would also be expected to undergo thermal and/or photochemical elimination of sulfur. [28][29][30][31][32][33][34][35] Starting with 15 Nlabeled 6-4-15 N, electrocyclic ring closure and sulfur elimination would lead to 15 N-labeled phenyldiazacyclobutadiene, which presumably would exist as an equilibrium mixture of 17a-15 N and 17b-15 N. Several reaction pathways can be envisioned for this species. First, as shown in Scheme 5, complete fragmentation of 17a-15 N and 17b-15 N would yield benzonitrile-14 N (5-14 N) and benzonitrile-15 N (5-15 N) in a 1:1 ratio.…”

Section: Resultsmentioning

confidence: 99%

“…It is plausible that triazines 7 and 8 can also arise from bicyclic species BC-6 . Thus, in addition to heteroatom migration leading to transposition (Scheme ), BC-6 would also be expected to undergo thermal and/or photochemical elimination of sulfur. − Starting with 15 N-labeled 6 - 4- 15 N , electrocyclic ring closure and sulfur elimination would lead to 15 N-labeled phenyldiazacyclobutadiene, which presumably would exist as an equilibrium mixture of 17a- 15 N and 17b- 15 N . Several reaction pathways can be envisioned for this species.…”

Section: Resultsmentioning

confidence: 99%

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Photochemistry of Phenyl-Substituted 1,2,4-Thiadiazoles. ¹⁵N-Labeling Studies

2003

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Irradiation of 5-phenyl-1,2,4-thiadiazole (6) resulted in the formation of benzonitrile (5), 3-phenyl-1,2,4-thiadiazole (4), phenyl- and diphenyl-1,3,5-triazines (7 and 8), and a trace quantity of diphenyl-1,2,4-thiadiazole (9). The formation of 4,5, 7, and 8 can be explained in terms of photoinduced electrocyclic ring closure resulting in the formation of an intermediate 4-phenyl-1,3-diaza-5-thiabicyclo[2.1.0]pentene. 15N-labeling experiments revealed that sulfur can undergo sigmatropic shifts around all four sides of the diazetine ring. Thus, irradiation of 6-4-15N led to the formation of 6-2-15N and an equimolar mixture of 4-2-15N and 4-4-15N. The thiabicyclo[2.1.0]pentene intermediate is also suggested to undergo sulfur elimination resulting in the formation of phenyldiazacyclobutadiene, which can undergo complete fragmentation to benzonitrile or [4+2] cycloaddition leading to unstable tricyclic adducts, the suggested precursors of the 1,3,5-triazine products 7 and 8. The observed 15N distribution in 7 and 8 is consistent with this mechanism. Irradiation of 4 led only to the formation of 5. 15N-labeling experiments show that 4 does not undergo electrocyclic ring closure but reacts exclusively by photofragmentation of the thiadiazole ring.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Photochemistry of Phenyl-Substituted 1,2,4-Thiadiazoles. ¹⁵N-Labeling Studies

2003

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1,4‐Dioxocin

1972

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J. Alrerihach und Dierev-Creinerl'J Herrn Professor R. Criegee ;urn 70. Geburtstag in Verehrung gewidmet Die Existenz und Aromatizitat des Cyclooctatetraen-Dianions['] regte in den letzten Jahren zu zahlreichen Versuchen an, die rnit dem Dianion isoelektronischen lox-Heterocyclen ( I a) -(I c), die 1,4-Diheterocine (1,4-Di-heter0[8]annulene)[~], zu synthetisieren. Diese Bemiihungen fuhrten inzwischen zwar zur Darstellung einiger nichtaromatischer Benzoderivate der 1,4-Dihetero~ine[~~, doch gelang es bisher nicht, die Stammverbindungen zu gewin-nenl4'.finische Protonen), 4.95 und 5.10 (2 CHBr-Protonen) sowie 6.09 und 6.30 ppm (2 epoxidische Protonen)] neben einem seiner beiden cis-3,6-Dibrom-Isomeren, sehr wahrscheinlich dem anti-l,2-Epoxy-cis-3,6-dibrom-4-cyclohexen ( 9 ) [Fp=97"C; Ausb. 5 % ; NMR (CDCI,): enge Multipletts bei r=4.17 (2 olefinische Protonen), 5.12 (2 CHBr-Protonen) und 6.28 ppm (2 epoxidische Protonen)], isolieren laat. 0 t 7 f 10) ( l a ) , X = 0 ( l b ) , X = XI1 ( I C ) , x = sUnser Interesse an derdrtigen 10 x-Heterocyclen, speziell am 1,4-Dioxocin (la), ergab sich zwangslaufig aus der Weiterentwicklung schon vor langerer Zeit begonnener Arbeiten iiber Synthese und Valenzisomerisierungen von Areno~iden[~. ' I. Wahrend sich Benzolmonoxid ( 2 ) bei Raumtemperatur in schnellem, energetisch ausgewogenem Gleichgewicht rnit Oxepin ( 3 ) befindetI5l, ist fur das bislang unbekannte syn-Benzoldioxid ( 4 ) zu erwarten, daD es relativ leicht eine orbitalsymmetrie-erlaubte [.Js +,2,

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