Stereoselective alkylation of thiacalix[4]arenes

Abstract A direct tetraalkylation of thiacalix[4]arenes using procedures well established in ‘classical’ calixarene chemistry usually gives the 1,3-alternate conformers as the main product ( n -PrI/K 2 CO 3 /acetone) while the cone conformers are obtained only in very poor yields ( n -PrI/NaH/DMF). Surprisingly, the so far almost inaccessible cone conformers can be prepared in high yields using the two-step procedure: dialkylation–dialkylation, opening the way for their further utilisation in supramolecular chemistry.