“…dioxane (8 mL), the mixture was stirred for 2-3 min, then corresponding diazacrown ether 15 or 16 (0.15 mmol) and t-BuONa (44 mg, 0.45 mmol) were added, and the reaction mixture was refluxed for 24-30 h. After cooling it down to ambient temperature the reaction mixture was diluted with CH 2 Cl 2 , the residue was filtered off, washed with dichloromethane, combined organic solvents were evaporated in vacuo, the residue was dissolved in CH 2 Cl 2 (5 mL), washed with distilled water (3×10 mL), organic layer was dried over molecular sieves 4 Å and evaporated in vacuo, and the residue was chromatographed on silica gel using a sequence of eluents: CH 2 [19.8.8.5 8,14 .1 2,6 .1 16,20 ]tetratetraconta-2(44), 3,5,16(38), 17,19-hexaene (20). 22, 25,30,7,10,13,19,13 .2 2,5 .2 15,18 ]tetratetraconta -2,4,15,17,36,43-hexaene (21 …”