Synthesis of New Sulfur Heteroaromatics Isoelectronic with Dibenzo[g,p]chrysene by Photocyclization of Thienyl- and Phenyl-Substituted Ethenes

Abstract

A series of new sulfur heteroarenes, isoelectronic with dibenzo[g,p]chrysene, have been prepared by double photocyclization of the corresponding tetraaryl substituted ethenes. The first step proceeds efficiently in each case, and the corresponding intermediate sulfur heteroarenes, isoelectronic with phenanthrene, have been isolated. The second ring closure is only efficient when one of the participating aryl substituents is thienyl, which thus manifests a higher electron density on the carbon atom involved in the excited singlet state reaction. Most of the new compounds are of minimal solubility in common solvents and do not display improved electron donor properties otherwise commonly found among heteroaromatics.

Aggregation-induced emission: mechanistic study of the clusteroluminescence of tetrathienylethene

“…12,54 To explore the AIE activity in the TTE system, we adopted a feasible synthetic route to obtain the locked structures of TTE (Scheme 2), 49 4,5-bis(thiophene-2-yl)thieno[3,2- e ]benzo[ b ]thiophene, (semi-locked TTE, sl-TTE) and tetrathieno[2,3- a :3′,2′- c :2′′,3′′- f :3′′′,2′′′- h ]-naphthalene (fully-locked TTE, fl-TTE). The sl-TTE compound was also further characterized using single crystal X-ray diffraction (Fig.…”

“…Herein, we report a small molecule, 1,1,2,2-tetra(thiophene-2-yl)ethene (tetrathienylethene, TTE, Chart 1 and Scheme 1), whose AIE feature was qualitatively observed previously. 48 In this work we have thoroughly investigated its AIE behaviour, and have rationalized the mechanism behind it, by synthesizing its locked counterpart, tetrathieno[2,3- a :3′,2′- c :2′′,3′′- f :3′′′,2′′′- h ]-naphthalene 49 (fully-locked TTE, fl-TTE, Scheme 2). The AIE mechanism of TTE accounts for the restriction of the intramolecular rotations (RIR).…”

New Applications of Hetaryl Thioketones for the Synthesis of Hetaryl-Substituted Ethenes via ‘Two-Fold Extrusion Reaction’

“…2 In addition, they are precursors of polyaromatic heterocycles, which can be prepared via photochemically induced oxidative cyclizations. 3 The synthesis of symmetrical aryl/hetaryl-substituted ethenes is based on the McMurry protocol, in which the corresponding aryl/hetaryl ketones are treated with TiCl 4 , Zn dust, and pyridine in boiling THF. 3,4 Recently, another method was reported, in which non-symmetrical ethenes are accessible.…”

“…3 The synthesis of symmetrical aryl/hetaryl-substituted ethenes is based on the McMurry protocol, in which the corresponding aryl/hetaryl ketones are treated with TiCl 4 , Zn dust, and pyridine in boiling THF. 3,4 Recently, another method was reported, in which non-symmetrical ethenes are accessible. In that case, an aryl/hetaryl ketone is initially converted to the corresponding gem-dibromoethene, which subsequently undergoes reaction with arene/hetarene via Suzuki-Stille coupling, leading to tetraaryl/hetaryl-substituted ethenes in decent yields.…”

“…In the latter case, diaryl thioketones react with diaryldiazomethanes with spontaneous elimination of N 2 to give thiiranes as exclusive products. 6 The subsequent desulfurization can be efficiently achieved using P(III)-compounds such as Ph 3 P or (Et 2 N) 3 P. This stepwise procedure is known as 'two-fold extrusion reaction'. 6a,7 In a recent publication we described a convenient method for the preparation of diaryl/hetaryl thioketones containing furan-2-yl, thiophen-2-yl, or selenophen-2-yl substituents.…”