An efficient one-pot four-component reaction has been developed for the synthesis of 2,4-diarylcyclooc-tenopyridines,in moderate yields. This route is an effective modified two-step synthesis of Krhnke pyridine and involves a four-component tandem reaction of pyridinium bromide with aromatic aldehydes and cyclooctanone in a system of NH4OAc/HOAc under microwave irradiation.
Under microwave irradiation,2,2'-alkoxy-bridging or 4,4'-alkoxy-bridging dibenzaldehydes reacted with 4-hydroxycoumarin in DMF to give a series of 3,3',3″,3'″-o-and 3,3',3″,3'″-p-phenylenedimethylidinetetrakis-(4-hydroxy-2H-1-benzopyran-2-ones) in moderate yields.The structures of the synthetic coumarin derivatives were characterized with IR,1H NMR and MS spectroscopy as well as X-ray single crystallography.
1,1'-Diacetoacetylferrocene 1 reacted with phenylene-1,3-dioxyactyl hydrazine 2 in absolute ethanol to give the macrocyclic ferrocenyl dipyrazole compound in moderate yield. Determined by X-ray structure analysis, it crystallizes in monoclinic system, space group P21/c with a = 13.7509(4), b = 8.1277(2), c = 21.7472(6) , β = 103.1030(10)°, V = 2367.25(11) 3, Z = 4, Dc = 1.505 g/cm3, R = 0.0353 and wR = 0.0811. The electrochemical studies reveal that redox of Fe+/Fe in ferrocene is a reversible one-electron process.
The regioselective syntheses of novel p-tert-butylcalix[4]arenes with functional aldehyde and dithiocar-bazate Schiff base groups were carried out.p-tert-Butylcalix[4]arene was alkylated with o-,H-(ω-chloroalkoxy)-benzaldehydes in the system of K_2CO_3/KI/CH_3CN to give calixarene 1,3-dialdehydes.Then the condensation reactions of active calixarene aldehydes with S-methyl and S-benzyldithiocarbazate,calixarene sulfur-containing Schiff bases were efficiently obtained in satisfied yields.The single crystal analysis of the four representative products shows that calixarene aldehydes and Schiff bases exist in cone conformation and there are interesting intermolecular hydrogen-bands andπ…πinteraction in the crystals.
The multicomponent reactions of 1,3-thiazolidinedione, malononitrile, aromatic aldehydes and α-phenylethylamine or β-phenylethylamine in acetonitrile at room temperature produce dihydrothiophene ureidoformamide derivatives in moderate yields through a domino ring-opening/recyclization reaction of 1,3-thiazolidinedione. On treatment with DDQ, dihydrothiophenes are dehydrogenated to convert efficiently to thiophenes in the mild condition.
SUN Jing, XIA ErYan, ZHANG LiLi & YAN ChaoGuo College of Chemistry & Chemical Engineering, Yangzhou University, Yangzhou 225002, China
Novel 1,3-distal p-tert-butylcalix[4]arene Schiff bases were efficiently synthesized in three steps. At first p-tert-butylcalix[4]arene was reacted with N-2-hydroxyethylphthalimide catalyzed by TPP/DEAD or alkylated with ω-haloalkylphthalimide in the system of K2CO3/KI/CH3COCH3 to give 1,3-distal diphthalimidoalkyl calixarenes, which were in turn hydrazinolyzed to give diaminoalkyl calixarenes. Then with the aid of the condensation of active calixarene amines with salicylaldehyde, 2-hydroxy-1-naphthaldehyde or pyridine-2-carboxaldehyde, a series of 1,3-distal calixarene Schiff bases was prepared in satisfied yields. The single crystal structures and complexing properties of these Schiff bases for transition metal ions were studied.
Under microwave irradiation, the one-pot multicomponent condensation reaction of three moles of aromatic aldehydes with two moles of cyclic ketones having free α,α'-methylene positions such as cyclopentanone or cyclohexanone in the presence of ammonium acetate and acetic acid afforded dicycloalkenopyridines with two α-arylidene groups in high yields. Under the similar reaction condition, the reaction of aromatic aldehydes with 1-tetralone having only one α-methylene position alternatively resulted in 10-aryl-2,3:5,6-dibenzoacridines.
