Synthesis of 2,4,6-triarylpyridines using phenacylidenedimethylsulfuranes

1 -Benzyl1 H-triazole-4,5dicarboxaldehyde (I) was prepared according to the procedure reported by Henkel and Weygand (5). The cyclic ketones were prepared according to the methods of Blomquist (6, 7). Melting points were determined with a Thomas-Hoover Unimelt instrument and are uncorrected. NMR spectra were recorded on a Varian A-60 spectrometer using tetramethylsilane as an internal reference and shifts (6) are reported in ppm. 1 -benzyl-5,7-dodecano -6 (2H )-cycloheptatrlazolone ( Z Z Z ) . A solution of 2.15 g (0.01 mol) of 1-benzyl-lH-triazole-4,5-dicarboxaldehyde and 2.24 g (0.01 mol) of cyclopentadecanone in 0.3 g of KOH and 50 mL of methanol was heated under reflux. After the mixture was cooled, the product was collected and then recrystallized from ethanol. 4-Hydroxy1 -benzyl-4,5-dlhydro-5,7-polymethyleno-6(2H )-cycloheptatrlazolones ( ZVa -c ). I n the same manner 2.15 g (0.01 mol) of l-benzyl-lH-triazole-4,5-dicarboxaldehyde and 0.01 mol of the corresponding cyclic ketones in 0.4 g of KOH and 60 mL of methanol was heated under reflux. The solvent was removed under pressure and the resulting product was recrystallized from chloroform-petroleum ether. The melting points, reflux time, yields, and NMR data for compounds I11 and IVa-c are listed in Table I.