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 Convenient Approach to 16‐, 19‐, and 22‐Membered 2,2′‐Bipyridine Thiacrown Ethers and Their Conformation Preferences

“…[14] In this work, we report a new approach to 1:1 thiacrown ether macrocycles and their sulfoxides incorporating a cyclopenteno[c]2,2Ј-bipyridine subunit, as well as X-ray crystallographic analysis of the target ligands. Our preliminary findings [15] and these studies suggest that this approach is fairly general for the preparation of large-sized rings, that is, rings having 13-22 or more atoms.…”

“…Bis(1,2,4-triazin-3-ylsulfanyl)-3,6-dioxaoctane (3a): Spectral data is described in a previous communication. [15] 1,11-Bis (1,2,4-trizin-3-ylsulfanyl) Bis(1,2,4-trizin-3-ylsulfanyl)-3,6,9 General Procedure for the Preparation of 5,5Ј-Bi-1,2,4-triazine-Containing Thiamacrocycles 4a-c and 10: A suspension of compound 3a-c or 9 (0.59 mmol) in water (134 mL) was stirred at 40°C until complete dissolution. After cooling to room temperature, potassium cyanide (0.137 g, 2.12 mmol) was added as a solid, and the resulting mixture was stirred for the period of time indicated in Table 1.…”

“…[15] 4,7,10-Trioxa-1,13-dithia [ X-ray Structure Determinations: X-ray data of 5a were collected with a Kuma KM4 diffractometer; crystal sizes 0.20 ϫ 0.20 ϫ 0.10 mm, Cu-K α (λ = 1.54178 Å) radiation, ω/2θ scans. Data collections for 5b, 5c, and 6b were performed with a Bruker SMART APEX II CCD diffractometer; crystal sizes 0.50 ϫ 0.24 ϫ 0.03 mm (5b), 0.42 ϫ 0.22 ϫ 0.14 mm (5c), and 0.35 ϫ 0.14 ϫ 0.07 mm (6b), Mo-K α (λ = 0.71073 Å) radiation, ω scans.…”

A facile approach to 2,2′-bipyridine based thiacrown ethers and their sulfoxides by DA-rDA reaction of 5,5′-bi-1,2,4-triazine thiamacrocycles. The conformation studies

“…Syntheses of 1,8-bis(1,2,4-triazin-3-ylsulfanyl)-3,6-dioxaoctane 3a, 1,11-bis(1,2,4-triazin-3-ylsulfanyl)-3,6,9-trioxaundecane 3b, 1,14-bis(1,2,4-triazin-3-ylsulfanyl)-3,6,9,12-tetraoxatetradecane 3c, 4,7-dioxa-1,10-dithia [10]3,3′-5,5′-bis(1,2,4-triazin-3-ylsulfanyl)cyclophane 4a, 4,7,10-trioxa-1,13-dithia [13]3,3′-5,5′-bis(1,2,4-triazin-3-ylsulfanyl)cyclophane 4b, 4,7,10,13-tetraoxa-1,16-dithia [16]3,3′-5,5′-bis(1,2,4-triazin-3-ylsulfanyl)cyclophane 4c were performed according to our published procedures. 6,7 General procedure for the preparation of thiacrown ethers (5a-c) and (6a-b) Method A. A solution of 2,5-norbornadiene (1.8 ml) in p-cymene (4 ml) containing compounds 4a-b (0.59 mmol) was heated for 20-24 h (see Table 1) at 140 °C.…”

“…4 However, synthetic efforts in this area have been hampered by the lack of the efficient methods of their synthesis. 5 In our preliminary work 6 we have shown that 1,2,4-triazine bis-sulfides, tethered to poly(ethylene glycol) chains undergo a remarkably facile, intramolecular cyclization into previously unknown 5,5′-bi-1,2,4-triazine thiacrown ethers (Scheme 1). The latter undergo an inverse electron demand Diels-Alder/retro Diels-Alder (DArDA) reaction with electron rich dienophiles affording bpy, or annulated bpy thiacrown ethers.…”