Synthesis of Polyfunctionalized Biphenyls as Intermediates for a New Class of Liquid Crystals

Abstract

A series of hexa- and octasubstituted biphenyls containing halogen, amino, nitro, and propylthio substituents were prepared by metal-mediated convergent synthesis from halobenzene precursors. The Pd-assisted C-C coupling methods were ineffective in the formation of the Ar-Ar bond except for the synthesis of 1b. All tetra-ortho-substituted biphenyls were prepared via Ullmann coupling reactions. The halogens were introduced after formation of the biphenyl by utilizing the directing properties of the amino group(s). In the case of 3b, a polyhalogenated benzene substrate was used for biphenyl formation via Ullmann coupling.

Effects of ortho‐ and para‐Ring Activation on the Kinetics of SNAr Reactions of 1‐Chloro‐2‐nitro‐ and 1‐Phenoxy‐2‐nitrobenzenes with Aliphatic Amines in Acetonitrile

“…102°C, (ref. [33] 106° were prepared by reaction at 45°C for two hours of the appropriate 1-chloro compound (1 equiv.) with potassium hydroxide (1 equiv.…”

Coarctate versus Pericyclic Reactivity in Naphthalene‐Fused Azo–Ene–Ynes: Synthesis of Benzocinnolines and Benzoisoindazoles

“…General procedure A-triazene formation: [21,22] To a flame-dried flask was added BF 3 ·OEt 2 (4 equiv) under an Ar atmosphere and the flask was cooled to À15 8C. Slowly, a solution of the naphthalenamine (1 equiv) in dry THF (0.24 m) was added such that the internal temperature stayed below À10 8C.…”

“…50 %), primarily due to the insolubility of the naphthalene derivative in the water/MeCN mixture. The yield could be improved to 81 % by using BF 3 ·OEt 2 and tBuONO in THF to generate the diazonium intermediate [21] followed by quenching with K 2 CO 3 and HNEt 2 in DMF. [22] Sonogashira cross-coupling with (trimethylsilyl)acetylene (TMSA) gave 13; subsequent protiodesilation afforded cyclization precursor 6.…”

Preparation of a discotic 2,4,7,9‐tetraaryl‐6H‐dibenzo[c,e][1,2]thiazine and generation of a persistent Radical

“…The biphenyl 3 was prepared by Suzuki coupling of 3,39,5,59-tetrabromo-2-nitro-29-propylthiobiphenyl (6) [11] and 3,4-dioctyloxyphenylboronic acid ethylene glycol ester [8]. The use of DME as a solvent instead of toluene gave higher yields of 3.…”