3-Arylisoxazolyl-5-carboxylic acid and 5-(Hydroxymethyl)-3-aryl-2-isoxazoline as molecular platforms for liquid-crystalline materials

• Autor(a) principal: Tavares,Aline
• Data de Publicação: 2009
• Outros Autores: Livotto,Paolo R., Gonçalves,Paulo F. B., Merlo,Aloir A.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Journal of the Brazilian Chemical Society (Online)
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532009000900025
• topic: 3,5-disubstituted isoxazolines; [3+2] 1,3-dipolar cycloaddition; liquid crystals; molecular platform

The synthesis of the molecular platform for liquid-crystalline materials based on 3-arylisoxazolyl-5-carboxylic acid (1) and 5-(hydroxymethyl)-3-aryl-2-isoxazoline (2) is described. The key intermediates 1 and 2 are obtained by [3+2] 1,3-dipolar cycloaddition reaction between an arylnitrile oxide and an acrylic acid and allylic alcohol as the dipolarophile. The liquid crystals (LC) compounds are synthesized through a "molecular elongation strategy" from the initial isoxazolinic core by connecting the arylacetylene moiety obtained from the Sonogashira reaction. Under these conditions, the series of liquid crystals 5a-c, 6, 7a-g and 8a-d have been successfully synthesized in fair to good yields. The final compounds display nematic and smectic liquid-crystalline properties. The structural properties of the series of the liquid crystals has been studied using DFT methods at level B3LYP/6-31G(d,p). The equilibrium geometries in the gas phase are presented and analyzed.