Über Reaktionen von 3‐Phenyl‐2 H ‐azirin mit kumulierten Doppelbindungen

Abstract

Die Cycloaddition eines Ketenimids oder Ketens an 3-Phenyl-2H-azirin (2) zum Vierring ist nicht symmetrieerlaubt. Uber nicht isolierbare Zwischenstufen verlaufen jedoch Cyclisierungen bzw. Cycloadditionen, die im Falle des Diphenylketen-p-tolylimids bei gleichzeitigcr Oxydation zu einem Gemisch aus Benzophenon, 2-0x0-7-methyl-5-phenyl-2.3dihydro-lH-1.3-benzodiazepin (11) und einem tricyclischen System 10 fuhren, das beim Erwiirmen irreversibel in 11 iibergeht. 2 reagiert mit Diphenylketen zum 6-Phenyl-2.4-bisdiphenylmethylen-3.5-dioxa-I -aza-bicyclo[4.1 .O]heptan (19). Die Strukturen werden mit Hilfe der Spektren und z.T. durch Abbaureaktionen zuerteilt. Reactions of 3-Phenyl-223-azirine with Cumulated Double BondsCycloadditions of keteneimines or ketenes to 3-phenyl-2H-azirine (2) to form a four-ring system are not symmetry-allowed. Cyclirations or cycloadditions via non-isolable intermediates take place, however, leading in the case of diphenylketene-p-tolylimine to a mixture of benzophcnone, 7-methyl-5-phenyl-2-oxo-2.3-dihydro-lH-l.3-benzodiazepine (ll), and a tricyclic system 10, the latter is transformed irreversibly into 11 on warming. 2 reacts with diphenylketene to give 2.4-bis(diphenylmethylene)-6-phenyl-3.5-dioxa-l-aza-bicyclo[4.1.0]heptane (19). The structures arc assigned with the aid of spectra and, in some cases, by degradation reactions.hn Rahmen unserer Untersuchungen ii ber I .5-Dipolare Cyclisieruiigen von Vinylazidenl) gelangten wir zum 3-Phenylimino-4-phenyl-l-aza-bicyclo[Z.l.O]pentan (3) und 3-Phenyl-2H-azirin (2) durch Bestrahlung von cc-Azido-styrol (1) in Benzol bei Raumtemperatur niit dem durch Pyrex-Glas gefilterten Licht einer Hochdruck-Quecksilberlanipe 2). Die Beobachtung einer charakteristischen Ketenimid-Ab-sorption3) bei 5 p iin TR-Spektrum unseres Reaktionsgemisches kurz nach der Photo-1 2 3

Tautomerism in drug discovery

“…If a labile proton attached to carbon migrates to N or O, although it is usually difficult to isolate pure individual tautomers, mixtures enriched in one tautomer can often be obtained [7][8][9]. However, if the migration is from N to O or O to O, proton exchange is so fast that one almost invariably obtains an equilibrium mixture, the position of which is dependent on the specific conditions (solvent/temperature).…”

Intramolecular cycloadditions of N-alkenoyl aryl azides

“…At this point it needs to be added that the absence of geminal coupling in the case of 6a parallels that observed for similar nitrogen bridgehead aziridines. 6,9 As a further stage of our work, we undertook the synthesis of [1,2,4]triazolo [4,3-a][1,4]benzodiazepin-4-ones 10 by means of nitrile imine cycloaddition onto the C᎐ ᎐ N double bond of imines 7a,b (Scheme 3). Hence, treatment of the latter with the hydrazonoyl chloride 8 10 in the presence of triethylamine, which generates nitrilimine intermediates 9, gave cycloadducts 10 with good yields and full regioselectivity.…”

PREPARATION, PROPERTIES AND SYNTHETIC APPLICATIONS OF 2H-AZIRINES A REVIEW

“…The ab inirio derived geometry and the calculated vibrational frequencies of 2-methylene-2H-azirines agree well with data obtained on the matrix-isolated species. 222 Downloaded by [Duke University Libraries] Bond lengths and angles for 2H-azirine 2 and 6.…”