Convenient Synthesis and Dichroic Properties of Heterocyclic Quinone Dyes, 3-(Dialkylamino)benzo[b]naphtho[2,3-d]furan-6,11-diones

Abstract

New heterocyclic quinone dyes, 3-(dialkylamino)benzo[b]naphtho[2,3-d]furan-6,11-diones, were conveniently prepared from 1,4-naphthoquinone and m-(dialkylamino)phenols. These dyes show dichroic properties and good solubility in a nematic liquid crystalline system.

Alternative Spiroketalization Methods toward Purpuromycin: A Hemiketal Conjugate Addition Strategy and Use of an Electron-Rich Isocoumarin Precursor

“…There is precedent for this type of conjugate addition cyclization, , the most recent by Tamura and co-workers, who were successful in adding a pendant nucleophile to a naphthaquinone electrophile under oxidative conditions (Figure ). The proposed forward mechanism as catalyzed by base is shown on a model system in Figure .…”

“…Of concern was the formal closure type being attempted (Figure ). Baldwin’s work shows that a 5- endo -trig type cyclization is disfavored but clearly possible according to the precedents above. − A formal closure of type 5- exo -trig may also be possible if the distal quinone acts as a strong electron-withdrawing group, allowing the nucleophilic addition of the hemiketal to the proximal aromatic ring. Our initial work utilized a benzene-based model system, but it soon became evident that this system was inadequate to mimic the reactivity of the naphthalene/naphthaquinone derivative of the naphthazarin.…”

“…3-Benzyloxy-6-bromo-4-hydroxymethyl-2-methoxy-benzaldehyde (27). To a solution of 26 (700 mg, 2.70 mmol) in dry DMF (35 mL) was added K 2 CO 3 (1.12 g, 8.09 mmol).…”

“…37 Mannich reaction and subsequent displacement of the N-acylated species with acetate furnished 25. 18 After hydrolysis of the acyl groups (26), the phenol was chemoselectively benzylated (27). Reduction of the aldehyde and bisacylation afforded Stille precursor 28.…”

Heterocyclic quinol-type fluorophores. Part 1. Synthesis of new benzofurano[3,2-b]naphthoquinolThe IUPAC name for the parent benzofurano[3,2-b]naphthoquinone is naphtho[2,3-b]benzofuran-6,11-dione. derivatives and their photophysical properties in solution and in the crystalline stateElectronic supplementary information (ESI) available: Table S1 containing crystal data and structure refinement parameters for 2c, 3c, and 3d. See http://www.rsc.org/suppdata/p2/b1/b109198k/

“…The starting 3-(dibutylamino)naphtho [2,3-b]benzofuran-6,11-dione dye 1 was prepared by the reaction of 1,4-naphthoquinone with m-(dibutylamino)phenol according to the procedure described in an earlier paper. 10 In order to obtain quinol-type compounds, compound 1 was allowed to react with organolithium reagents (RLi: MeLi, BuLi, and PhLi) at Ϫ108 ЊC. Aqueous work-up and purification by column chromatography gave the isomeric pairs of quinols 2a-2c and 3a-3c together with recovery of 1 (Table 1).…”