Synthesis and evaluation of novel tetrapropoxycalix[4]arene enones and cinnamates for protection from ultraviolet radiation.

A series of novel calix[4]arene enones (5-7) and cinnamates (12-14) have been synthesized and evaluated for ensuring protection from ultraviolet radiation (UVR). Spectroscopic analyses has revealed that compound 6 absorbs ultraviolet radiations between 280 and 350 nm with an absorption maximum at 312 nm. Its molar absorption coefficient (ε) (>5 × 10(4)M(-1)cm(-1)) and bandwidth are larger than those for the commercially used sun protectants (oxybenzone (OB), 2-ethylhexyl 4-methoxycinnamate (OMC) and avobenzone).

Convenient direct synthesis of bisformylated calix[4]arenes via ipso substitution.

[reaction: see text] A facile synthesis of bisformylated calix[4]arenes via ipso substitution of p-tert-butylcalix[4]arenes through treatment with hexamethylenetetramine/trifluoroacetic acid is described. Under identical conditions, p-tert-butylcalix[4]arene tetramethyl ether 4 gives proximally substituted bisformylated derivative 4a in a pinched cone conformation.