Reductive methylation of triphthaloylbenzene: Isolation and characterization of hexamethoxy-trinaphthylene and two unexpected trinaphthylene derivatives. Issue 43 (22nd October 2020)

• Record Type: Journal Article
• Authors: Nishida, Keigo; Ono, Katsuhiko; Kato, Shin-ichiro; Kitamura, Chitoshi
• Is Part Of: Tetrahedron letters. Volume 61:Issue 43(2020)
• Publication Date: 2020-10-22
• Subjects: Trinaphthylene -- Polycyclic aromatic hydrocarbons -- Curvature -- Ruductive methylation -- X-ray crystallography; Chemistry, Organic -- Periodicals; 547.005
• DOI: 10.1016/j.tetlet.2020.152422
• Languages: English
• ISSNs: 0040-4039

Abstract

Graphical abstract: Highlights: Reductive methylation of triphthaloylbenezene was complicated. Two unexpected products except for hexamethoxy-trinaphthylene were isolated. X-ray crystallographic analysis of two compounds exhibit deformed cores. Optical properties of three compounds were examined. Adding DBU into a peculiar compound possessing hydroxy groups causes a color change. Abstract: With the aim of developing new π-conjugated materials for application in electronics, the reductive methylation of triphthaloylbenzene is presented. Several new products are obtained: 5, 6, 11, 12, 17, 18-hexamethoxy-trinaphthylene (1a ) and two unexpected compounds, i.e., the corresponding monohydroxy-pentamethoxy-trinaphthylene (1b ) and a peculiar trinaphtylene derivative (2 ) possessing hydroxy, methoxy, carbonyl, and ketal groups and a tetrahydrofuran moiety fused on the core. X-ray crystallographic analysis of 1b and 2 reveals that both compounds exhibit deformed frameworks. The investigation of their optical properties shows that the lowest-energy absorption bands for 1a and 1b are a shoulder band around 350 nm, whereas 2 gives rise to a one broad and weak band at 573 nm. All the molecules have negligible fluorescence. Addition of 1, 8-diazabicyclo[5.4.0]undec-7-ene into a solution of 2 causes a color change from purple to olive brown, which renders it suitable as a pH indicator.