A divergent approach was developed toward the total synthesis of taiwaniaquinoids. An advanced intermediate 5a with trans A/B ring junction was concisely assembled by employing a Bi(OTf)3-catalyzed cationic cyclization and a Wolff-type ring contraction as key steps. This common intermediate was readily converted to racemic taiwaniaquinones A and F and taiwaniaquinols B and D, respectively.

The mechanism of the cycloaddition reaction between singlet state dichlorosilylene germylidene (Cl2Si=Ge:) and acetone has been investigated with B3LYP/6-31G* and B3LYP/6-31G** method, from the potential energy profile, we predict that the reaction has one dominant reaction pathway. The presented rule of the reaction is that the two reactants firstly form a Si-heterocyclic four-membered ring ge...

The mechanism of protein synthesis is still unknown due to inability to detect the so-called enzyme "peptidyl transferase" even after elucidation of high-resolution crystal structure of ribosome. We have recently shown by model building and semi-empirical energy calculation that the tRNA molecule at P-site of ribosome may act as peptidyl transferase (Das et al. (1999) J. Theor. Biol. 200, 193-2...

in this note we introduce the notion of weak mccoy rings as a generalization of mccoy rings, and investigate their properties. also we show that, if is a semi-commutative ring, then is weak mccoy if and only if is weak mccoy.

substituted 2, 4- diphenyl quinolines were synthesized by a multicomponent domino reaction of anilines, aldehydes and terminal aryl alkynes. the synthetic pathway involves the formation of an imine, followed by the intermolecular addition of an alkyne to the imine. this intermediate immediately undergoes ring closure and oxidative aromatization. the reaction is catalyzed by natural kaolin, a st...

HIE-124 is a new member of ultra-short acting hypnotics’ drug family. In this research, the synthesis ofanalogues of HIE-124 drug in the heterocyclic thiazole ring replaced to thiadiazole, will be presented.Thiadiazolodiazepines during a two-step reaction starting from the amino thiadiazole resultedfrom-various derivatives of benzoic acid and thiosemicarbazide were synthesized. In the first ste...

Substituted pyrroles may be synthesized from selected 1,2-pyridazines through a reductive ring contraction involving the addition of four electrons and four protons. Our density functional theory computations of this reaction mechanism show that the first reduction event must be preceded by the uptake of one proton by 1,2-pyridazine and that the reaction proceeds through a 2e(-)/3H(+)-bearing i...

HIE-124 is the new member of ultra-short acting hypnotics drug family. In this research, thiadiazole can act as the bio-isosteric replacement of thiazole in synthesized compounds as HIE-124 derivatives. HIE-124 drug, in which the heterocyclic thiazole ring replaced to thiadiazole, will be presented. Thiadiazolodiazepines were synthesized by a two-step reaction starting from the amino thiadiazol...