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

Abstract

Abstract. Intramolecular photochemical reactions of thiophene analogues of o-distyrylbenzene, 2,2'-(o-phenylenedivinylene)dithiophenes (1a,b), 3,3'-(o-phenylenedivinylene)dithiophene (2a) and 3,3'-(o-phenylenedivinylene)dibenzothiophene (2b), were studied in acidic media at low concentrations. A 1,6-and 1,5-ring closure of hexatriene system leading to dihydronaphthalene or indene derivatives, respectively, was observed. (doi: 10.5562/cca2120)

Mechanistic insights into the thermal transformations of heterocyclic o-distyrylbenzenes: an experimental and computational study

“…3 In addition to well-known photochemical transformations of distyrylbenzenes, [4][5][6][7][8][9][10][11][12][13] over the past years, their thermal transformations in neutral and acidic [14][15][16][17][18][19] were also studied. 20 While thermal reaction in neutral medium did not indicate significant reactivity, acidic conditions can cause protonation of the double bond and the formation of new intramolecular products. So far, thermal transformations in acidic media of different substituted thiophene derivatives have been studied, wherein the reactivity depended significantly on the structure of starting compounds and position of sulphur in the heteroaromatic moiety (Scheme 1).…”

Formation of Polycyclic Skeletons by Photochemical Transformations of Pyridyl‐ and Thienylbutadiene Derivatives

“…[2] When properly functionalized, bicyclo[3.2.1]octanes have proved to be useful reactive intermediates in stereoselective transformations. [5] During our long-standing studies in photochemical intramolecular cycloaddition reactions of various -heteroaryl-o-divinylbenzenes such as furans, [6][7][8] thiophenes, [8][9][10] pyrroles, [11,12] sydnones, [13][14][15] and most recently oxazoles, [16][17][18] routes were obtained for a whole library of polycyclic compounds that include a vast number of structures with the benzobicyclo[3.2.1]octadiene moiety (A-D) (Scheme 1). [3,4] The benzobicyclo[3.2.1]octadiene skeleton can thus be even more useful, as it can easily be transformed by adding various functional groups to the isolated double bond.…”

“…For the first time, a study of efficiency was conducted where the efficiency of intramolecular cycloaddition of these heterocyclic butadiene derivatives was investigated by simultaneous use of ferrioxalate and valerophenone actinometers. From vast previous studies of the excited state behavior conducted on stilbene moieties, [7][8][9][10][11][12][13][14][15][16][17][18] it was expected that butadiene derivatives would give, by intramolecular photocycloaddition, a new line of polycyclic products. [19] Derivatives that have been investigated so far have been those with phenyl and 2-furyl substituents (Scheme 2).…”

“…[19] Derivatives that have been investigated so far have been those with phenyl and 2-furyl substituents (Scheme 2). From vast previous studies of the excited state behavior conducted on stilbene moieties, [7][8][9][10][11][12][13][14][15][16][17][18] it was expected that butadiene derivatives would give, by intramolecular photocycloaddition, a new line of polycyclic products. Desired derivatives with the benzobicyclo[3.2.1]octadiene skeleton (G) as well as polycyclic products H were synthesized, purified, and described (Scheme 2).…”

Photochemical approach to functionalized benzobicyclo[3.2.1]octene structures via fused oxazoline derivatives from 4- and 5-(o-vinylstyryl)oxazoles

“…Various methodologies and new synthetic approaches for their preparation and reactivity have been reviewed [ 3 ]. Continuing our long-standing interest for photochemical intramolecular cycloaddition reactions of various β-heteroaryl- o -divinylbenzenes, furans [ 4 – 6 ], thiophenes [ 6 – 8 ], pyroles [ 9 – 10 ] and sydnones [ 11 – 13 ], as routes to polycyclic compounds, we turned our attention to oxazole derivatives. The oxazole structure is commonly found in natural products and pharmaceuticals [ 14 – 17 ] and is applied in useful reagents and intermediates in organic synthesis [ 18 – 25 ].…”