Synthesis and Photochemistry of Styryl Substituted Annelated Furan Derivatives

Synthesis and Photochemistry of β,β′‐Di(2‐furyl)‐Substituted o‐Divinylbenzenes: Intra‐ and/or Intermolecular Cycloaddition as an Effect of Annelation

“…The stereoselective formation of the exo isomer can be explained (Scheme 3) by the preferred trans ring closure to the indane intermediate 20, presumably for steric reasons. Then, 20 ringcloses via 22 by the same mechanism as seen in the reactions of the mono-furan and mono-benzofuran derivatives of o-divinylbenzene [1,4,6] to yield exo-12, -13, and -14, respectively. The formation of the endo isomer, found only in traces (12,14), can be explained by cis ring closure to give the indane intermediate 21, which, via 23, gave endo-12 and endo-14.…”

“…The singlet assigned to proton A is the more affected and is shifted strongly toward a low field owing to the anisotropic effect of the benzene and naphthalene rings, respectively. In the previously obtained bicyclo[3.2.1]octadiene derivatives [1,2,4,6] with no substituent on the methano bridge carbon, proton A couples only with the exo-oriented proton and appears as a narrow doublet. As the endo-oriented proton does not couple with proton A the exo structure was assigned.…”

“…[1][2][3][4][5][6][7][8] Furan (1) and benzo[b]furan (2) derivatives of o-divinylbenzenes give, upon irradiation in dilute petroleum ether or benzene solutions, benzobicyclo[3.2.1]octadiene derivatives 4 [1] and 5, [4] respectively, as the main photoproducts (Scheme 1). No intramolecular cycloaddition product was found upon irradiation of the naphthofuran derivative 3 [4] in dilute solution under the same conditions. The only observed products were traces of dimeric cyclobutane derivatives.…”

Photochemical and Thermal Transformations of Thiophene o-Distyrylbenzene Analogues in Acidic Media

“…Our recent research on the intramolecular photochemical reactions of conjugated thiophene derivatives 1,2 continues the work on furan [3][4][5][6][7][8][9][10] and pyrrole [11][12][13][14][15][16] derivatives of o-divinylbenzenes. Dithiophene derivatives 1, 2 react differently 2 in comparison to previously studied difuran 3 8 and dipyrrole 4 12 derivatives ( Figure 1).…”

Synthesis and photochemistry of β-(3-substituted-2-furyl)-o-divinylbenzenes; [2+2] and [4+2] intramolecular cycloadditions

“…[1][2][3][4][5][6][7][8][9][10] This work has been extended to furan (1b) [11][12][13][14][15][16] and pyrrole (1c) [17][18][19][20][21] analogues. It has been found that contrary to o-vinylstilbene (1a), which undergoes an intramolecular [2+2] photocycloaddition that generates benzobicyclo[2.1.1]hexene structure (2), the furano analogue (1b) gives benzobicyclo[3.2.1]octadiene structure (3a) while the pyrrolo analogue (1c) reacts completely different and is transformed into an intermolecular adduct.…”