Syntheses of All Possible O-Methylation Products Derivable from 5,11,17,23,29,35-Hexa-tert-butylcalix[6]arene-37,38,39,40,41,42-hexol

We here report methods for the synthesis of all twelve possible O-methylation products from 5,11,17,23,29,35-hexa-tert-butylcalix[6]arene-37,38,39,40,41,42-hexol (1): one mono-, three di-, three tri-, three tetra-, one penta-, and one hexamethylated products. The strategies used are (i) direct O-methylation with different 1/K₂CO₃ ratios, (ii) selective mono-O-methylation of O-alkylation products, (iii) demethylation with TiCl₄ or LiI, and (iv) protection-deprotection with a benzyl group or an o- or m-xylenyl group. We believe that these O-methylation products are useful as basic skeletons to design functionalized calix[6]arenes with the desired number of substituents and regioselectively-positioned functional groups.