Materiais moleculares funcionais contendo n-heterociclos - capes

Hockey stick-shaped LC compounds 383Scheme 1. Reagents: a. p-bromobenzoyl chloride, pyridine; b. 1-bromoalkane, K 2 CO 3 , butanone; c. 1) 2-methyl-3-butyn-2-ol,PdCl 2 (PPh 3 ) 2 , CuI, TPP, TEA; 2) NaOH, toluene; d. ethyl chloroformate, K 2 CO 3 , butanone; e. I 2 , NaHCO 3 ,CH 2 Cl 2 /H 2 O; f.NH 2 NH 2 .H 2 O, KOH, ethylene glycol; g. 1) 2-methyl-3-butyn-2-ol, PdCl 2 (PPh 3 ) 2 , CuI, TEA/THF; 2) NaOH, toluene; h. 1) 1-decylbromide, butanone, K 2 CO 3 , KI; 2) KOH, MeOH/H 2 O; 3) HCl conc.; i. DCC, DMAP, 4-ethynylphenol, CH 2 Cl 2 ; j. compound9, PdCl 2 (PPh 3 ) 2 , CuI, TPP, TEA.Table 1. Results of the palladium cross-coupling using theroute from scheme 1 for compounds 1–7.CompoundYield/%1 542 493 564 not isolated a5 656 557 not isolated aa Only homocoupling product.the characteristic focal-conic fan texture. This may beexplained by the presence of a piperazine ring in themolecule. This ring is preferentially present in the chairconformation with substituents being arranged inequatorial positions [22]. The polarity and polarizabilityof the molecule backbone is increased by mutualconjugation between the lone electron pair of thenitrogen and the oxadiazole ring. It is known that thesecharacteristics tend to favour smectic properties [23].Compound 7 exhibits the most stable liquid crystallineprofile, with a melting point of 129.1uC and a widesmectic (an unidentified SmX and SmC) and nematicrange. Upon cooling, the schlieren nematic texture