Photochemical transformations of 3,3,4,7-tetramethylpyrazolo[3,4-d]pyridazine in solution and frozen gas matrices

Huben, Krzysztof; Kuberski, Sławomir; Frankowski, Andrzej; Gębicki, Jerzy; Streith, Jacques

doi:10.1039/c39950000315

Cited by 8 publications

(10 citation statements)

References 5 publications

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“…1 H NMR (300 MHz) d 2.10 (3H, s), 1.99 (3H, s), 1.64 (6H, s). 13 5.11. Irradiation of 4,6-di-tert-butyl-3,3-dimethyl-3H-thieno [3,4-…”

Section: Irradiation Of 3346-tetramethyl-3h-thieno[34-c]pyrazole 24mentioning

confidence: 98%

“…The following abbreviations have been used: s (singlet), d (doublet), t (triplet), q (quartet), m (multiplet), br (broad). 13 C assignments were made with the aid of DEPT experiments. Mass spectra were measured on a VG Autospec.…”

Section: Photochemistry Of 3h-thieno[34-c]pyrazolesmentioning

confidence: 99%

“…1). 13,14 2. Synthesis of 3H-furo [3,4-c]pyrazoles and 3H-thieno [3,4-c] pyrazoles 3H-Thieno [3,4-c]pyrazoles and 3H-furo [3,4-c]pyrazoles have not been synthesized to date and few tautomeric thieno [3,4-c] pyrazoles are known.…”

Section: Introductionmentioning

confidence: 99%

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Photochemistry of 3H-furo[3,4-c]pyrazoles and 3H-thieno[3,4-c]pyrazoles

Payne

2013

Tetrahedron

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“…1 H NMR (300 MHz) d 2.10 (3H, s), 1.99 (3H, s), 1.64 (6H, s). 13 5.11. Irradiation of 4,6-di-tert-butyl-3,3-dimethyl-3H-thieno [3,4-…”

Section: Irradiation Of 3346-tetramethyl-3h-thieno[34-c]pyrazole 24mentioning

confidence: 98%

Section: Photochemistry Of 3h-thieno[34-c]pyrazolesmentioning

confidence: 99%

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Photochemistry of 3H-furo[3,4-c]pyrazoles and 3H-thieno[3,4-c]pyrazoles

Payne

2013

Tetrahedron

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“…Shortly afterwards, the isolation of the first heterocyclic cycloproparene 105 was achieved by irradiation of the pyrazolopyridine 104, [30] and this photodeazetation route has been extended to the preparation of the cyclopropapyridazine 110 (Scheme 20). [31] In the latter example, irradiation of precursor 107 in a matrix at 10 K provided evidence for the intermediacy of diazo compound 108 in the formation of alkene 111, but not of cycloproparene 110. [31] The mechanistic details of the photodeazetation of some 3H-indazoles of relevance to the precursors in Scheme 20 have been probed in more detail by Kirmse and coworkers.…”

Section: Cyclopropa-fused Heterocyclesmentioning

confidence: 99%

“…[31] In the latter example, irradiation of precursor 107 in a matrix at 10 K provided evidence for the intermediacy of diazo compound 108 in the formation of alkene 111, but not of cycloproparene 110. [31] The mechanistic details of the photodeazetation of some 3H-indazoles of relevance to the precursors in Scheme 20 have been probed in more detail by Kirmse and coworkers. [32] in methanol [29] can be explained by a similar protonation pathway.…”

Section: Cyclopropa-fused Heterocyclesmentioning

confidence: 99%

Nonbenzenoid Cycloproparenes

Wege¹

2001

Eur. J. Org. Chem.

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Despite the extensive literature on cycloproparenes, compounds possessing cyclopropa-fusion to functionalised benzenoid rings or to nonbenzenoid aromatic systems are rare. This review describes approaches to some of these novel systems. The cyclopropaquinones 29 and 30, generated by bromodesilylation at −78°C of precursors 47 and 70, respectively, are too reactive to be isolated, but can be trapped as Diels−Alder adducts with furan. The high reactivity of 29 and 30 contrasts with the stability of quinones 24 and 26 in which the quinone moiety and cyclopropa-fusion are located in different rings. The cycloaddition methodology developed for the generation of 30 has been extended to the synthesis of favelanone (98), a natural product incorporating the cyclopropa[b]naphthalene-2,7-dione structural motif. While several six-membered heterocyclic cycloproparenes have been CycloproparenesThe fusion of a cyclopropene ring to an aromatic ring generates a family of theoretically interesting compounds known as cycloproparenes, exemplified by the parent member benzocyclopropene (1) and benzo-fused derivatives such as 1H-cyclopropa[a]naphthalene (2), 1H-cyclopropa[b]-naphthalene (3) and 1H-cyclopropa[l]phenanthrene (4) (Scheme 1). The chemistry of cycloproparenes has been reviewed extensively [1] and only those aspects that are relevant to the present Microreview are mentioned below. Much of the interest in the chemistry of cycloproparenes arises from the high reactivity of the three-membered ring and the geometrical and reactivity perturbations imposed upon the benzenoid ring as a result of the ring-fusion; hence this area [a] 849 described, the synthesis of cyclopropafurans and cyclopropathiophenes poses significant challenges. There is tentative evidence for the generation of the cyclopropa[c]thiophene 160 by double dehydrobromination of 158, but the photolysis of the pyrazolothiophene 166 yields only alkene 169 and none of the desired ring-closed product. In contrast, irradiation of the related pyrazolofuran 165 results in clean fragmentation to give the acetylenic enone 171. The cyclopropatropone 201 has been prepared, and the derived hydroxytropylium ion 202 represents the first example of a cyclopropafused seven-membered aromatic ring system. Finally, while the synthesis of cyclopropazulenes remains to be achieved, the potentially useful precursor 230 has been obtained by a directed transannular aldol condensation.

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References

2000

Chemistry of Heterocyclic Compounds: A Series of Monographs

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Photochemical transformations of 3,3,4,7-tetramethylpyrazolo[3,4-d]pyridazine in solution and frozen gas matrices

Cited by 8 publications

References 5 publications

Photochemistry of 3H-furo[3,4-c]pyrazoles and 3H-thieno[3,4-c]pyrazoles

Photochemistry of 3H-furo[3,4-c]pyrazoles and 3H-thieno[3,4-c]pyrazoles

Nonbenzenoid Cycloproparenes

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