Bithiazoles

In the reverse reaction, thioheteroaryl amides reacted under reflux in alcohol with haloketones or aldehydes to give the corresponding 2-heteroarylthiazole derivatives (238, 271, 482, 550, 751, 765, 776, 781). 2,2 -Bithiazoles (4,4 -disubstituted) have been obtained in 80 to 90% yield by cyclocondensation of 1 mole rubeanic acid with 2 moles of a-bromoketones in polyphosphoric acid at 95 to 135 C (780). Some multiheteroaryl substituted thiazoles have been also reported (704). 

The same lithium salts with copper(I) chloride react through the stage of the anionic C-coordinated complexes 100, which on protonation with hydrochloric acid give the corresponding 2,2 -bithiazoles, with triflic acid— the N-coordinated species 101, and on methylation with methyl triflate they give carbenes of structure 102. 

Bithiazole, 2,2 -btz = (96), is a diimine, but it coordinates much less strongly than bipy to Fe2+ 9 [Pe(2,2 -btz)3](C104)2 exists in two modifications with slightly different magnetic proper-... 

A 100-ml Schlenk flask was charged with the step 1 product (0.231 mmol), 5,5 -bis(5-bromo-2-thienyl)-4,4 -dihexyl-2,2 -bithiazole (0.231 mmol), tris(dibenzy-lideneacetone)dipalladium (0) (0.00231 mmol), triphenylphosphine (0.0162 mmol), and Aliquot 336 (0.0855 mmol). The flask was evacuated and refilled with argon... 

The structure for the step 2 reagent, 5,5 -bis(5-bromo-2-thienyl)-4,4 -dihexyl-2,2 -bithiazole, (I), is indicated below. 

Such design concepts were first reported utilizing 2,2 -bithiazole and 2,2 -bi-pyridine units, respectively, as postpolymerization metal coordination sites [349, 350]. Subsequently, a poly(p-phenylenevinylene)-based polymer 69 containing ionic ruthenium centers bound to bipyridyl (BPY) units incorporated into the polymer backbone was reported. This system, depicted in Scheme 68, exhibits enhanced photoconductivity relative to the parent organic polymer [351] (Yu). 

Subsequently, preparation of macrocycle 215 (Scheme 87), containing four thiazole units involved two steps. Diformylation of 4,4 -di(tert-butyl)-2,2 -bithiazole to obtain 214 and subsequent McMurry coupling furnished 215 (00HCA1161). 

Treating 2-bromothiazole with copper at 170 °C in cumene as solvent affords the 2,2 -bithiazole. 

Monomers not commercially available were prepared by known methods 4,4 -bis(p-aminophenyl)-2,2 -bithiazole (22), 2,5-bis(p-aminophenyl )oxadiazole (22), N,NMbis( p-aminophenyl )isophthalamide (27), 2V,N -m-phenylenebis(m-aminobenzamide) (23), and 1,4-bis(p-amino-phenyl) butadiene (16). Cuprous chloride was obtained by ascorbic acid reduction of CuCl2 according to Stathis (26). 

The high temperature resistant polyamides, a poly(isophthalamide) of 4,4 -bis(p-aminophenyl)-2,2 -bithiazole) (TEA), a poly-terephthalamide of l,3-bis(3-aminobenzamido)benzene (M3P), and the aromatic polyamide Nomex (DuPont), were studied by Johnson et al. [31], Activation spectra for discoloration and strength loss were obtained using a prism-dispersed spectrum from a xenon source using a technique similar to that used by Hirt and Searle [19]. 

Lu, W, Kuwabara, J., Kanbara, T., 2012. Synthesis of 4,4 -dinonyl-2,2 -bithiazole-based copolymers via Pd-catalyzed direct C—H arylation. Polym. Chem. 3, 3217-3219. 

Synthesis oxidative eleetropolymerization of bis(3,4-ethylene-dioxythiophene)-4,4 -dinonyl-2,2 -bithiazole) in diehloromethane/TBAPFe or TEABF4 [721]. 

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