Stereocontrolled Synthesis and Characterization ofcis-Poly(arylenevinylene)s

Abstract

A highly stereocontrolled synthesis of five kinds of cis-poly[(arylenevinylene)-alt-(2,5-dioctyloxy-1,4-phenylenevinylene)]s has been accomplished by Suzuki−Miyaura-type polycondensation [arylene = p-phenylene (3af), m-phenylene (3bf), 4,4‘-biphenylene (3cf), 2,7-fluorenylene (3df), 9,9-dihexyl-2,7-fluorenylene (3ef)]. Reactions of (Z,Z)-bis(2-bromoethenyl)arenes (1a − e) with 2,5-dioctyloxybenzene-1,4-diboronic acid (2fx) in toluene in the presence of Pd(PPh3)4 catalyst, aqueous KOH base, and Bu4NBr as a phase-transfer catalyst at 80 °C for 24 h form 3af − ef with number-average molecular weight (M n) of 5700−9500 in 77−99% yields. The stereoregularity of vinylene linkages in the polymer backbone has been found at least 95%. The starting monomers (1a − e) were prepared in almost geometrically pure forms (≥99% cis), either by ruthenium-catalyzed hydrosilylation of diethynylarenes followed by bromodesilylation of the resulting bis(2-bromoethenyl)arenes or by addition of bromine to arenediacrylic acids followed by debrominative decarboxylation promoted by Et3N. MALDI-TOF-MS analysis of cis-3af has revealed the presence of two types of polymers having different end groups. Type I polymer bears (Z)-4-(2-bromoethenyl)phenyl and 2,5-dioctyloxyphenyl group at each end, whereas type II polymer has 2,5-dioctyloxyphenyl groups at both ends. Type I polymer is successfully converted to type II polymer by palladium-catalyzed reaction with 2,5-dioctyloxybenzeneboronic acid to obtain cis-poly[(p-phenylenevinylene)-alt-(2,5-dioctyloxy-1,4-phenylenevinylene)] in a single form.

Novel One-Pot Synthesis of Functionalized (Z)-2-Arylvinyl Bromides

“…Compound 2, carrying a carboxyl group, is a new synthon for preparation of various derivatives that are useful intermediates in organic synthesis. [1][2][3][4][5][6] The proposed reaction pathway for the present debrominative decarboxylation is shown in Scheme 2. The reaction probably proceeds via trans-elimination involving simultaneous loss of carbon dioxide and bromide ion to give (Z)-vinyl bromides (Scheme 2).…”

“…[1,2] The coupling products from functionalized (Z)-2-arylvinyl bromides have found numerous applications in the preparation of pharmaceuticals, functional polymeric material, and natural products. [3][4][5][6] Although there is a need to incorporate functional groups into (Z)-2-arylvinyl bromides to find novel functionalized compounds, available synthetic methods are limited in scope. Traditional methods for preparation of (Z)-2-arylvinyl bromides can be classified into two major categories.…”

“…The first method is palladium-catalyzed hydrogenolysis of 1,1-dibromo-1-alkenes by tributyltin hydride. [3] The second method is the debrominative decarboxylation of cinnamic acid dibromides. [4][5][6][7][8][9] This method might be one of the most useful method for synthesis of (Z)-1-bromo-1-alkenes because the starting a,b-unsaturated acids are readily available and the procedure is very simple.…”

Poly(p‐phenylene vinylene) Derivatives with Different Contents of cis‐Olefins and their Effect on the Optical Properties

“…Thus, it is critical to synthesize PPV polymers with different amounts of the cis-configurations. The synthesis of geometrically-pure all-cis PPVs by Suzuki-Miyaura-type polycondensation has been reported in previous work, [16,17] as well as some research about PPVs with different contents of cis-and trans-olefins, synthesized by the Wittig and Wittig-Horner reactions; however, the olefin bond geometry was random, and the luminescence properties of PPVs with different cis-contents have not been studied systemically. [14,15,18] In this report, we have synthesized a DPO-PPV with the highest cis-configuration of up to 87% using the Wittig reaction.…”

Pseudo‐Living Anionic Telomerization of Buta‐1,3‐diene

“…[11][12][13] While a variety of matrices have been reported in the literature, most synthetic polymers have been analyzed using 1,8,9-trihydroxyanthracene (dithranol), 2,5-dihydroxybenzoic acid (DHB), 2-[4-(hydroxyphenyl)azo]benzoic acid (HABA), trans-3-indoleacrylic acid (IAA), and 2,4,6-trihydroxyacetophenone (THAP). [10] The determination of polymer end groups using MALDI-TOF MS is generally accepted and reported widely in the literature; [14][15][16][17][18][19][20][21][22][23][24][25][26] however, the analysis of liquid PBs, as described herein, remains unprecedented.…”