Zongbiao Ding

A facial synthesis of the neutral [1,2,4]triazolo-[3,2-d][1,5]benzoxazepines and their chalcogen-analogues

ABSTRACT An expedient synthesis of neutral [1,2,4]triazolo[3,2-d][1,5]-benzoxazepines 6a–e and their chalcogen analogues 6f–i was accomplished via cycloaddition of the heterocumulene cations (3a,b), generated sequentially by action of chroman-4-one as well as thiochroman-4-one ethoxy carbonylhydrazones (1a,b) with t-BuOCl and SbCl5, to the triple bond of nitriles and concurring ring enlargement and hydrolytic removal of the N(1)-ethoxycarbonyl group. The oily final products were characterized as their picrates.

A Facile Synthesis of 1,3,5-Triaryl Benzenes from Acetophenone Diethyl Ketals in the Presence of Acetyl Chloride and SmCl3

Abstract Samarium trichloride, SmCl3, has been found to be an efficient catalyst for the synthesis of 1,3,5-triaryl benzenes from acetophenone diethyl ketals in the presence of acetyl chloride under solvent of pentane and mild conditions.

A Facile Method for the Transformation of Acetals and Ketals to Aldehydes and Ketones

Abstract This paper reports a simple and convenient acetyl chloride-samarium trichloride system for the transformation of acetals and ketals to aldehydes and ketones

A DFT study on dissociation of diborane (B2H6) in dimethyl sulfide media

Abstract The detailed dissociation mechanism of diborane (B 2 H 6 ) in dimethyl sulfide (Me 2 S) media has been studied at the levels of B3LYP/6-311G**//B3LYP/6-31G* and B3PW91/6-311G**//B3PW91/6-31G*. All the calculations predict a two-step mechanism for the dissociation and only one H-bridge bond is broken in each. In comparison with the dissociation of B 2 H 6 in vacuum or in hydrocarbon media, the participation of Me 2 S significantly lowers the activation barriers in the process. The barriers are even more lowered when solvent effect is embraced.

SYNTHESIS OF HYDROXYCEDRANONE AND AMINOHYDROXYCEDRANE

Abstract Two optically pure derivatives of α-cedrene — (1R,2R,5S,7R,8R)- 8-hydroxy-9-cedranone 2 and (lR,2R,5S,7R,8R,9S)-9-amino-8-hydroxycedrane 4 were prepared conveniently. An X-ray structural analysis of 2 was performed indicating that the hydroxycedranone exists as dimer due to one hydrogen bond in solid state.

ASYMMETRIC HOMOLOGATION OF CEDRANEDIOL BORONIC ESTERS AND X-RAY STRUCTURE OF CEDRANEDIOL 1-CHLORO-1-PHENYLMETYLBORONATE

Abstract Homologation of cedranediol boronic esters 1, RBO,C15H,4l with (dichloromethyl)lithium resulted in the formation of (αR)-α-chloro boronic esters 3, RCHCIBO2C15H24, consistently yielding (R)/(S)ratios over 25:1. The absolute configuration of cedranediol (R)-1-chloro-1-phenylmethylboronate 3dR was determined by X-ray diffraction. The distortion of the five-membered 1,3,2-dioxaborolane ring of 3dR from planarity was found. The reason why the cedranediol boronic esters are prone to hydrolysis has been discussed.

PREPARATION OF CEDRANEDIOL BORONIC ESTERS

Abstract (-)-Cedranediol boronic esters 4, a series of asymmetric homologation reagents were prepared from a new chiral director (-)-cedranediol 3 and boronic acids. (-)-Cedranediol 3 was easily synthesized by the dihydroxylation of (-)-α-cedrene 2 with OsO4. A more convenient method for the preparation of boronic acids was developed as well.

A facile route to poly[1-(2,4,6-trichlorophenyl)-1H-1,2,4-triazol-5-yl]alkane derivatives

The synthesis of the tetrakis{2-[1-(2,4,6-trichlorophenyl)-1H-1,2,4-triazol-5-yl]ethoxymethyl}methane derivatives 5a–c, 6 and 7, and the nitrotris{2-[1-(2,4,6-trichlorophenyl)-1H-1,2,4-triazol-5-yl]ethyl}methane derivatives 9a–c, 10 and the picrate 11 has been accomplished by reaction of the 1-aza-2-azoniaallene salts 3 with either the aliphatic tetranitrile 1 or trinitrile 8, in high yields; the X-ray crystal structure of 5b is also reported.

A Convenient Synthesis of 4,5-Diaryl-1,8-Dihalo-3,6-Dioxaoctanes

Abstract A kind of useful precursors for the construction of vicinal diaryl-substituted macrocycles, 4,5-diaryl-1,8-dihalo-3,6-dioxaoctanes, was readily produced by reductive coupling of aromatic carbonyl compounds with 2-haloethanols in the presence of tin powder and chlorotrimethylsilane in moderate to good yields by a one-pot procedure.