Synthesis, chemical and physical properties of 2,3-diaza bicyclo[3.2.0] heptadienes

Luttringer, J. P.; Perol, N.; Streith, Jacques

doi:10.1016/0040-4020(75)80250-x

Cited by 6 publications

(1 citation statement)

References 29 publications

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“…Similar results have been obtained by us (7,8) and by others (9) during uv irradiation of a series of diazepines which gave the corresponding bicyclic isomers having the same skeleton as 2. We expected, therefore, that the azetidinodiazepines 3 would undergo a similar disrotatory ring closure during direct ultraviolet irradiation of their conjugated diene moiety.…”

Section: Direct Ultraviolet Irradiation Of Azetidinodiazepines 3a-3dsupporting

confidence: 77%

Photoinduced isomerization reactions of azetidinodiazepines

Tschamber¹,

Streith²,

Strub³

et al. 1984

Can. J. Chem.

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. 62, 2440 (1984).Ultraviolet irradiation of the azetidinodiazepines 3 leads in good yield to the expected tricyclic isomers 4 which represent potential precursors for the synthesis of 3-azacarbapenam derivatives. The rigid boat-shaped topology of the photoisomers 4 could be ascertained by detailed 'H and I3C nmr measurements, and in particular by the determination of nuclear Overhauser effects. That only the syn stereoisomers 4 are formed is most likely due to the conformation of the precursors 3 in which the convex side of the seven-membered ring is syn with respect to the p-lactam ring. Triplet sensitized irradiation of 3, which should specifically give a T* + n transition of the azetidinocarbonyl function, leads to the highly strained anti-Bredt isomers 5 whose structures were determined by 'H and, especially, by I3C nrnr measurements. The structure of 5 a was also established by an X-ray analysis which shows, in particular, that the bridgehead imine double bond is twisted out of plane by about 20". Thermal activation of the anti-Bredt compound 5 a leads to a mixture of the two isomers 8 and 9 which are more stable than 5 a by about 40 kcal/mol as determined by differential scanning calorimetry. L'irridation ultraviolette des azCtidinodiazCpines 3 conduit, avec de bons rendements, aux isomeres tricycliques attendus 4 qui reprksentent des prCcurseurs potentiels pour la synthkse de dCrivCs aza-3 carbapCnames. Des mesures de rmn du 'H et du "C et, en particulier, des mesures d'effet Overhauser nuclCaire permettent d'ttablir que le photoisomere 4 posskde une topologie de forme bateau rigide. Le fait que seuls les stCrioisom&res syn 4 se foment est probablement dQ la conformation des prCcurseurs 3 dans lesquels la portion convexe du cycle a sept chainons est en position syn par rapport au cycle du p-lactame. L'irradiation, sensibilisie par un triplet, du compose 3, qui devrait conduire d'une faqon spicifique B une transition T* + n de la fonction azCtidinocarbonyle, conduit plutBt aux isomeres 5 qui sont fortement tendus et qui n'obiissent pas a la regle de Bredt; on a determink leurs structures en faisant appel a la rmn du 'H et plus encore la rmn du I3C. On a tgalementCtabli la structure du composC 5 a par diffraction des rayons-X qui montre, en particulier, que la double liaison de I'imine sur la t&te de pont est tordue hors du plan d'environ 20". L'activation thermique du produit anti-Bredt 5 a conduit a un mClange des deux isomkres 8 et 9. La calorimitrie diffkrentielle a balayage montre que ces derniers sont plus stables que leur prCcurseur 5 a d'environ 40 kcal/mol. [Traduit par le journal]

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Section: Direct Ultraviolet Irradiation Of Azetidinodiazepines 3a-3dsupporting

confidence: 77%

Photoinduced isomerization reactions of azetidinodiazepines

Tschamber¹,

Streith²,

Strub³

et al. 1984

Can. J. Chem.

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ChemInform Abstract: SYNTHESIS, CHEMICAL AND PHYSICAL PROPERTIES OF 2,3‐DIAZABICYCLO(3.2.0)HEPTADIENES

Luttringer¹,

Perol²,

Streith³

1975

Chemischer Informationsdienst

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Photochemistry of 3‐Substituted 1‐Iminopyridinium Ylides. Regiospecific versus non‐regiospecific photoisomerization patterns [1]

Fritz

Gleiter

Nastasi

et al. 1978

Helvetica Chimica Acta

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3-Substituted 1-iminopyridinium ylides 1 undergo photo-induced ring enlargement to 1 H -1,2-diazepines. With strongly electron-withdrawing substituents the ring expansion process is regiospecific and leads exclusively to 4-substituted 1 H-1,2diazepines. Weak electron-donating substituents, like a methyl group and halogen atoms, do not have any directing effect since both 4-and 6-substituted 1 H-1,2-diazepines are obtained. With strong electron-donating substituents no diazepines are formed; instead one observes photo-induced isomerization to the 2-aminopyridine derivatives, the process being non-regiospecific. Regiospecific photo-induced ring expansion processes are explained in terms of a simple HMO model.Introduction. -The photo-induced ring enlargement of 1 -iminopyridinium ylides 1, which leads to the isomeric 1 H-1,2-diazepines 3, is a well established ring transformation [2]. The scope and limitation of this rearrangement have not been studied in great detail so far. Therefore, we have investigated directing effects of substituents, attached to C (3) of the ylides 1, on the ring enlargement process. I ) *) Basel. 3, Darmstadt. 4, Mulhouse. Part 10 of the series 'Photochemical Synthesis of 1,2-Diazepines'. Part 9: [I71 -7.5; m J = 7 J = 7 , 3 J= 3 J = 7.5, 4.5 J= 4.5 J = 8 , 4 . 5 J = 7.5,2 J= 7.5, 4 J = 8.5 J=8.5, 2 J = 2 J = 7.5, 5 29 2 12-213a) 8.3; d, 7.3; d x d, J= 8 J = 8 , 2 a) M.p. of the picrate. b, 6 [ppm], J[Hz].

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Synthesis, chemical and physical properties of 2,3-diaza bicyclo[3.2.0] heptadienes

Cited by 6 publications

References 29 publications

Photoinduced isomerization reactions of azetidinodiazepines

Photoinduced isomerization reactions of azetidinodiazepines

ChemInform Abstract: SYNTHESIS, CHEMICAL AND PHYSICAL PROPERTIES OF 2,3‐DIAZABICYCLO(3.2.0)HEPTADIENES

Photochemistry of 3‐Substituted 1‐Iminopyridinium Ylides. Regiospecific versus non‐regiospecific photoisomerization patterns [1]

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