Nguyen Chung Thanh

Synthetic methods for preparing 1,3-di(2-pyridyl)azulene

The title compound was synthesized either by introduction of another pyridine ring into 3-(2-pyridyl)-l,2,3,8-tetrahydroazulen-l-one or by Stille and Negishi double cross-coupling reactions of 1,3-dihaloazulenes with the corresponding 2-pyridyl reagents.

Synthesis and properties of polycyclic quinones condensed with 1,6-methano[10]annulene

Abstract Two types of polycyclic quinones condensed with 1,6-methano[10]annulenes as type A: 1,6-methanonaphtho[2,3-c][10]annulene-7,12-dione 5a, and type B: 1,6-methanonaphtho[2,3-c][10]annulene-5,14-dione 18, bis(1,6-methano[10]annuleno[3,4-b; 3,4-g])anthracene-10,21-dione 20, 1,6-methanoanthraceno[2,3-c][10]annulene-5,16-dione 22, 1,6-methanotetraceno[2,3-c][10]annulene-6,17-dione 23, and 1,6-methano phenanthreno[2,3-c][10]annulene-5,6-dione 24 have been synthesized. The acene derivative 6 corresponding to that of 5a was synthesized by the reduction of quinone 5a. The physical, spectral, and chemical properties of these new compounds have been investigated.

Synthesis and structural analysis of 3,6,8,11,16-hexahydrodicyclohepta[c,h][1,6]dithiecin

The cycloaddition reaction of 3,6,9-trihydrocyclohepta[c][1,2]dithiin (5), prepared from 3,4-bis(bromomethyl)-1,3,5-cycloheptatriene (3) in two steps, with 3,4-dimethylene-l,5-cycloheptadiene (6) in the presence of boron trifluoride-etherate gave 3,6,8,11,16-hexahydrodicyclohepta[c,h][1,6]dithiecin (2). The temperature-dependent NMR study indicated that 2 possesses the fluxional tetrahydrodithiecin moiety in solution at room temperature. The X-Ray crystal structure analysis showed that 2 has an S-letter shape which was supported as the most stable conformer by DFT molecular orbital calculations.

Out-of-plane deformation of the azulene ring along its short molecular axis in crystal and theoretical structures of 1,3-diheterolyl- and 1,3-diphenylazulenes

Crystal structures of four simple azulene derivatives, 1,3-diheterolyl-and 1,3-diphenylazulenes, were determined by X-ray diffraction analysis. Three of them showed clear out-of-plane deformation of the azulene ring along its short molecular axis, and one showed a similar but very small deformation. Structural and conformational analyses on substituted azulenes were also performed by DFT molecular orbital calculations. Based on the results of the calculations it was indicated that azulenes could exhibit such deformation depending on their conformations except one case, supporting the results of X-ray analysis. A similar deformation was also found in the crystal structure of a previously reported 1,3-disubstituted azulene whose data were collected from an X-ray crystal structure database.

WITHDRAWN: Synthesis, Structure and some Reactions of a Multi-bridged Unsaturated Cyclooctadecane Derivative Formally Having Two Cycloheptatrienes

Double annulation of 1,6-bis(bromomethyl)-1,3,5cycloheptatriene with diethyl acetonedicarboxylate under basic conditions provided the title cyclooctadecane derivative having formally two 1,3,5cycloheptatriene moieties. An NMR study of the compound suggested that one moiety stays as a cycloheptatriene form and the other as a norcaradiene form. X-ray crystallographic analysis revealed that two methano bridges have synand anti-configurations to the central carbonyl bridge and also showed that one of the moieties having the syn-methano bridge stays a CHT form and the other having the anti-methano bridge stays an NCD form.