Torand cyclization

Caution Carry out all procedures in a well-ventilated hood, and wear disposable vinyl or latex gloves and chemical-resistant safety goggles. 

Set up the magnetic stirrer and oil bath and use the power cord to attach the heating element to the variable transformer. Clamp the thermometer so that it will be as close to the pressure tube as possible. 

Combine the 3,4,7,9,10,12,13,14-octahydroacridino[4,3-b]benzo[y][1,10]-phenanthroline-1,15(2H,6H)-dione, the 3,6-bis(dimethylaminomethylene)-2,3,7,8-tetrahydroacridine-4,5(1H,6H)-dione, and the acetic acid in the pressure tube, add the stirrer bar and close the tube. Swirl the contents in the tube until all solids are dissolved. Add 1.2 mL (13 mmol) of trifluoromethanesulfonic acid, and seal the tube. 

Immerse the pressure tube in the oil bath at least up to the level of the contents. Heat the bath to 100°C and stir the mixture in the tube for 1.5 h. Remove the tube from the oil bath and allow it to cool for 15 min. 

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Diketone 12 must be condensed with a third, doubly functionalized octahydroacridine unit in the last step of the torand synthesis (cf Scheme 6.1). The following protocols (8-10) describe the three-step synthesis of torand precursor 15 from octahydroacridine 5. The reagents involved in these three steps are shown in Scheme 6.11. According to Protocol 8, octahydroacridine is condensed with benzaldehyde in the presence of acetic anhydride,24 as in the second stage of Protocol 2 (cf Scheme 6.3). The crystalline product 13 precipitates from the reaction mixture in high yield and purity. Ozonolysis of 13 (Protocol 9) is conducted by the method described in Protocol 7 for conversion of 11 to diketone 12 (cf. Scheme 6.10) and the same precautions apply. The product diketone 1425 requires no further purification after removal of benzaldehyde by trituration with diethyl ether. The third octahydroacridine unit is then readied for torand cyclization in Protocol 10 by condensing diketone 14 with Bredereck s reagent, r-butoxybis(dimethylamino)methane,26 which is commercially available. The bis[p-(dimethylamino)]enone product 15 is easily purified by precipitation from ether/dichloromethane. 

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