Sequential homo-coupling Diels-Alder/retro Diels-Alder reaction of 5,5′-bi-1,2,4-triazine-containing thiamacrocycles as a new route to thiacrown ethers incorporating a 2,2′-bipyridine subunit

A new route to thiacrown ethers 5a-d and 6a-d incorporating a 2,2 '-bipyridine subunit is elaborated using, (1) homo-coupling of 1,2,4-triazine sulfides 3a-d tethered to poly(ethylene glycol) chains with potassium cyanide and (2) Diels-Alder/retro Diels-Alder reaction with norbornadiene or I-pyrrolidino-l-cyclopentene as the key steps. (c) 2007 Elsevier Ltd. All rights reserved.