The synthesis of [18]annulene trisulphide

Abstract

[18]Annulene 1,4:7,10:13,16-trisulphide has been synthesized. It has been found to be a stable non-planar non-aromatic system in which the three thiophen rings are linked by three essentially olefinic vinylene groups.

Dithiaethyneporphyrin: An Atypical [18]Triphyrin(4.1.1) Frame for Contracted Porphyrins

“…[6][7][8] Herein, we report the synthesis and characterization of 3,8,13,18-tetraphenyl-19,21-dithiaethyneporphyrin (H(S 2 -ETPP); 3). This porphyrin derivative is a novel type of contracted heteroporphyrin related to putative [18]triphyrin-(4.1.1) with an acetylene moiety embedded in the macrocyclic framework.…”

New amidino‐benzimidazolyl thiophenes: Synthesis and photochemical synthesis

“…Compound 2b was also prepared by the McMurry reaction in the mixture with E isomer 2a by treatment of thiophene-2-carbaldehyde with a low-valent titanium reagent, prepared from titanium(IV)chloride and zinc powder in boiling THF [23]. Compound 2b was formylated into 1,2-di[(5formyl)2-thienyl]ethene (3) by Vilsmeier formylation [24]. Dialdehyde 3 was photochemically dehydrocyclized into 2,7-bis-formyl-benzo[1,2-b:4,3-b ] (7) by the reaction of photochemical dehydrogenation described earlier [21].…”

“…• C (lit [24] mp 240-241 • C). Concentrated hydrochloric acid was added to the filtrate and additional crystalline crops consisting of the E isomer were filtered off.…”

“…Compound 3 was prepared by the Vilsmeier reaction described earlier [24] from 2b (3.00 g, 24 mmol) in DMF (10 ml) by dropwise addition of (with stirring and cooling) POCl 3 (10 ml) in such a way that the temperature of the reaction mixture did not exceed 10 • C. After complete addition, the mixture was stirred for 30 min at room temperature, and then heated at 90-95…”

“…The precipitated Z isomer 1b was filtered off and recrystallized from methanol. It was obtained in a yield of 6.80 g (42%) as light yellow crystals of mp 239-241 • C (lit [24] mp 240-241 • C). Concentrated hydrochloric acid was added to the filtrate and additional crystalline crops consisting of the E isomer were filtered off.…”