Aryl derivatives polymer synthesis

The synthetic route represents a classical ladder polymer synthesis a suitably substituted, open-chain precursor polymer is cyclized to a band structure in a polymer-analogous fashion. The first step here, formation of the polymeric, open-chain precursor structure, is AA-type coupling of a 2,5-dibromo-1,4-dibenzoyl-benzene derivative, by a Yamamoto-type aryl-aryl coupling. The reagent employed for dehalogenation, the nickel(0)/l,5-cyclooctadiene complex (Ni(COD)2), was used in stoichiometric amounts with co-reagents (2,2 -bipyridine and 1,5-cyclooctadiene), in dimethylacetamide or dimethylformamide as solvent. 

An alternative synthesis of a thermally stable cyclopentadienyl functionalized polymer involved ring bromination of poly(oxy-2,6-diphenyl-l,4-phenylene), followed by lithiation with butyl lithium to produce an aryllithium polymer. Arylation of 2-norbornen-7-one with the metalated polymer yielded the corresponding 2-norbornen-7-ol derivative. Conversion of the 7-ol to 7-chloro followed by treatment with butyl lithium generated the benzyl anion which undergoes a retro Diels-Alder reaction with the evolution of ethylene to produce the desired aryl cyclopentadiene polymer, 6. 

The Ni Bt2(bpy) complex was found to be an efficient catalyst precursor, not only in the synthesis of ArSAr derivatives, but also in the catalytic formation of ArSeAr compounds (via the cross-coupling reaction of aryl selenols). Polymer-supported borohydride was used as a reducing agent and polymer-supported aryl iodide as a reagent. The reaction was carried out with high yield and resulted in high purity of the products leading to the construction of a library of supported species (Scheme 3.21) [48]. 

Due to the utility of the methods and the significance of the materials, the use of Pd-catalyzed fV-arylation reactions in oligoaniline and polyaniline synthesis has remained an active area of research [344, 345]. For example, in recent work Kulszewicz-Bajer and coworkers have employed Pd-catalyzed amination reactions for the synthesis of AT-aryl poly(w,-p-aniline) derivatives that can be oxidized to high-spin radical cations [346, 347]. The preparation of these materials was accomplished by coupling 1,3-dibromobenzene with A TV -diarylphenylenediamine derivatives (Eq. 65). Palladium-catalyzed A -arylation reactions have also been employed for the preparation of partially annulated poly(w-anilines) [348] and other triarylamine-derived polymers [349, 350]. 

Substituted 4-aryl-1 -oxo-1,2-dihydropyrazino[l, 2-i]isoquinolinium salts 402 were obtained when 3-substituted isoquinolines 401 were cleaved from a polymer by treatment 25% TFA (00MIP5). c/i-3,lla-H-3-Phenyl-1,2,3,4,11,11 fl-hexahydropyrazino[l, 2-i]isoquinoline-1,4-dione (404) formed when isoquinoline derivative 403 was cleaved from a resin with 25% TFA during an automated solid-phase synthesis (98BMCL2369). 

The utility of the stepwise, double-coupling procedure is demonstrated in the parallel synthesis of Tamoxifen derivatives on solid support [127] (Scheme 1-29). 1-Alkenylboronates thus obtained by a diboration-cross coupling sequence are further coupled with p-silyUodobenzene supported on polymer resin. Using this strategy, each position about the ethylene core is modified by the appropriate choice of alkyne, aryl halide, and cleavage conditions for the synthesis of a library of Tamoxifen derivatives. 

Zinc chloride-doped natural phosphate was shown to have catalytic behavior in the 1,3-dipolar cycloadditions of nucleoside acetylenes with azides to form triazolonucleosides <99SC1057>. A soluble polymer-supported 1,3-dipolar cycloaddition of carbohydrate-derived 1,2,3-triazoles has been reported <99H(51)1807>. 2-Styrylchromones and sodium azide were employed in the synthesis of 4(5)-aryl-5(4)-(2-chromonyl)-1,2,3-triazoles <99H(51)481>. Lead(IV) acetate oxidation of mixed bis-aroyl hydrazones of biacetyl led to l-(a-aroyloxyarylideneamino)-3,5-dimethyl-l,2,3-triazoles <99H(51)599>. Reaction of 1-amino-3-methylbenzimidazolium chloride with lead(fV) acetate afforded l-methyl-l/f-benzotriazole <99BML961>. Hydrogenation reactions of some [l,2,3]triazolo[l,5-a]pyridines, [l,2,3]triazolo[l,5-a]quinolines, and [l,2,3]triazolo[l,5-a]isoquinolines were studied <99T12881>. 

An optimised solid-phase method for the generation of diverse a-amino-alkyl or -aryl phosphonates derived from peptides and polymer-assisted solution-phase parallel synthesis of dipeptide p-nitroanilides and dipeptide diphenyl phosphonates have been reported. A modular method for the construction of polypeptides containing the Phe-Arg phosphinic acid isostere has been described. A novel methodology for the solid-phase synthesis of phosphinic peptides has been developed in which the phosphorus-carbon bond was formed... 

A solid-phase synthesis of biaryls has been described by Forman and Sucholeiki [133] they used both phenyltrialkyltins with polymer-supported aryl iodides or the reverse technique involving polymer-supported aryltributyltins and aryl iodides or triflates. The fonmer approach was preferred, even though overall yields were poor. Related chemistry has been reported by Plunkett and Ellmann [134], who prepared 1,4-benzodiazepine derivatives via an initial solid-phase reaction between an aryltin moiety and acid chlorides (Scheme 4-38). 

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