Iodine as novel reagent for the 1,2-addition of trimethylsilyl cyanide to ketones including α,β-unsaturated ketones

Molecular iodine is found to catalyze efficiently the addition of trimethylsilyl cyanide to a range of simple and functionalized ketones under very mild and convenient conditions to afford the corresponding cyanohydrin trimethylsilyl ethers in excellent yields in a short reaction period with high selectivity. α,β-Unsaturated ketones selectively afford the corresponding 1,2-adducts without the formation of 1,4-adducts under similar reaction conditions.     

Reactions on a solid surface. A simple, economical, and efficient acylation of alcohols and amines over Al2O3

Al(2)O(3) brings about a rapid acylation of a range of alcohols and amines with acid chlorides and acid anhydrides, respectively. Amines are easily Boc- and Cbz-protected on reaction with Boc-anhydride and Cbz-Cl, respectively. The acylation of phenols is slow enough to allow chemoselective acylation of alcohols and amines in the presence of phenols.     

Stereoselective syntheses of (+)-proto, (−)-gala quercitols and carba-l-rhamnose from d-(−)-quinic acid

Efficient syntheses of (+)-proto, (−)-gala quercitols and carba-l-rhamnose from d-(−)-quinic acid are described.     

Novel mercaptoacetylative expeditious annulation of 5-mercaptopyrimidine ring on azoles using 1,3-oxathiolan-5-one

Schiff bases of azoles containing the amino group as part of a partial amidine structure undergo mercaptoacetylative expeditious annulation with 2-methyl-2-phenyl-1,3-oxathiolan-5-one to yield highly substituted 6,7-dihydro-6-mercapto-5H-thiazolo/1,3,4-oxa(thia)diazolo[3,2-a]pyrimidin-5-ones stereoselectively. The annulation is effected via an isolable intermediate under solvent-free microwave irradiation conditions in a one-pot procedure.     

Synthesis of bicyclo[3.2.1]octanones via ketyl radical promoted rearrangements under reductive PET conditions

Photoinduced electron transfer (PET) reactions from triethylamine (TEA) to ketones have been utilized for a clean and efficient route to bicyclo[3.2.1]octanones. A one-pot conversion of bicyclo[2.2.2]octenones to such molecules has been described. MeOH as well as acetonitrile/LiClO₄ combinations have been found to be the most effective solvents for these reactions.     

Solvent-free one-pot reactions for annulating a pyrimidine ring on thiazoles under microwave irradiation

One-pot reactions of glycine, acetic anhydride and thiazole Schiff bases (2a-f) diastereoselectively and expeditiously annulate a pyrimidine ring on the thiazole nucleus to yield 6,7-dihydro-5H-thiazolo[3,2-a]pyrimidin-5-ones (4a-f) under microwave irradiation and solvent-free conditions.     

Synthesis and anti-inflammatory activity of 2,3-diaryl-4(3H)-quinazolinones

2,3-Diaryl-4(3H)-quinazolinones containing various substituents on diaryl rings have been synthesized and evaluated for their cyclooxygenase-2 inhibitory activity by the colorimetric COX (ovine) inhibitor screening assay and anti-inflammatory activity by the carrageenan-induced rat paw edema assay. 2-(4-Nitrophenyl)-3-(4-tolyl)-4(3H)-quinazolinone showed a maximum COX-2 inhibition of 27.72% at 22 μM concentration in the present series and exhibited a mild anti-inflammatory activity at a dose of 50 mg/kg in carrageenan-induced rat paw edema assay. Published in Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1198–1205, August, 2006.     

Interatomic and intraatomic analysis of the density matrix: applications to chlorobenzenes

Bond orders and valence indices have been evaluated employing Mayer’s definitions with orthogonalized atomic orbitals (OAO) obtained from L?wdin orthogonalization over an STO-3G basis set in anab initio formalism. It has been observed that the eigenvalues of the submatrices associated with bond order orbitals. natural hybrid orbitals and natural bond orbitals also reproduce the same values of the bond orders and the valence indices which in turn are quite close to the classical values. Bond orders obtained by a similarity transformation of theab initio density matrix differ appreciably in numerical magnitude.     

First use of a palladium complex with a thiosemicarbazone ligand as catalyst precursor for the Heck reaction

A novel palladium complex with salicylaldehyde N(4)-ethylthiosemicarbazone has been synthesized and according to its crystal structure the ligand is bound to the metal in an O, N, S-terdentate coordination mode. This phosphorus-free system efficiently catalyzes the Heck reaction of aryl bromides (from electron-rich to electron-poor) with styrene under argon, with turnover numbers of up to 43,000, at 150 °C after 24 h, and with a selectivity toward trans-stilbenes ranging from 92 to 96%. In air, for activated aryl bromides and for a palladium concentration of 1 mM, the yields are essentially the same as those obtained when the reaction was performed under argon.