Synthesis, Structures and Conformational Studies of 1,2-Dimethyl[2.10]metacyclophan-1-enes

Thamina Akther (1) , Md Monarul Islam (1) , Shofiur Rahman (2) , Paris Georghiou (2) , Taisuke Matsumoto (3) , Junji Tanaka (3) , Pierre Thuéry (4) , Carl Redshaw (5) , Takehiko Yamato (1)

1 Department of Applied Chemistry
2 MUN - Memorial University of Newfoundland = Université Memorial de Terre-Neuve [St. John's, Canada]
3 Institute of Materials Chemistry and Engineering (Japan)
4 LCMCE - Laboratoire de Chimie Moléculaire et de Catalyse pour l'Energie (ex LCCEF)
5 University of Hull [United Kingdom]

A series of 1,2‐dimethyl[2.10]metacyclophan‐1‐enes (MCP‐1‐enes) containing different substituent groups has been synthesized to illustrate their conformational behavior. 4,22‐dimethoxy‐1,2‐dimethyl[2.10]MCP‐1‐ene 3 was synthesized by a Grignard coupling reaction, Friedel‐Crafts acylation reactions and McMurry coupling reaction from 1,10‐dibromodecane. The formation of 4,22‐dihydroxy‐1,2‐dimethyl[2.10]MCP‐1‐ene 4 was carried out by demethylation of compound 3 with boron tribromide at room temperature. The syn type conformation of 4 was characterized by X‐ray diffraction and was found to form both intramolecular and intermolecular hydrogen bonds between the two hydroxyl groups. From this reaction an interesting compound [10]tetrahydrobenzofuranophane 5 was afforded on prolonging the reaction time. 5,21‐diformyl‐4,22‐dihydroxy‐1,2‐dimethyl[2.10]MCP‐1‐ene 6 has been prepared from 4,22‐dihydroxy‐1,2‐dimethyl[2.10]MCP‐1‐ene 4 by using the Duff method in the presence of hexamethylenetetramine. Structural analysis by 1H NMR spectroscopy and X‐ray diffraction confirmed that both the solution and the crystalline state of compound 6 adopts an anti‐conformation which forms an intramolecular hydrogen bond between the formyl group and the hydroxyl group, which is an interesting finding for long carbon chain MCP compounds.

Domains: Organic chemistry; Cristallography

Thamina Akther, Md Monarul Islam, Shofiur Rahman, Paris Georghiou, Taisuke Matsumoto, et al.. Synthesis, Structures and Conformational Studies of 1,2-Dimethyl[2.10]metacyclophan-1-enes. ChemistrySelect, 2016, 1 (13), pp.3594 - 3600. ⟨10.1002/slct.201600670⟩. ⟨cea-01758720⟩