Synthesis of New Primary-Tertiary Alkyl Bisperoxides by Reaction of Tertiary Hydroperoxides with Bromoalkanesin a PTC System

Summary.  Syntheses of novel primary-tertiary bisperoxides were carried out under phase transfer catalysis conditions. The bisperoxides were obtained in good yields, the reaction times not exceeding four hours. Received January 15, 2001. Accepted (revised) February 9, 2001     

Sulfuric Acid: A Mild Catalyst for the Regioselective Synthesis of 2-Substituted [1,2,4]Triazolo[5,1-b][1,3]thiazin-7-ones

Summary.  A facile and regioselective synthesis of 2-substituted [1,2,4]triazolo[5,1-b][1,3]thiazin-7-ones by action of sulfuric acid on (4H-[1,2,4]triazol-3-ylsulfanyl)-acrylic acids is described. Received January 23, 2001. Accepted (revised) May 7, 2001     

Potassium Ferrate Supported on Montmorillonite K-10: A Mild and Efficient Reagent for Oxidative Deprotection of Acetals and Ketals

Summary.  A variety of acetals and ketals were oxidatively deprotected to their parent compounds using potassium ferrate(VI) supported on montmorillonite K-10 under non-aqueous conditions. Received January 23, 2001. Accepted (revised) March 14, 2001     

Mild,Efficient, and Rapid Dehydration of Aldoximes to Nitriles Mediated by Phthalic Anhydride Under Microwave Irradiation

Summary.  Aldoximes can be efficiently and rapidly dehydrated to nitriles by treatment with phthalic anhydride under microwave irradiation. Received April 18, 2001. Accepted (revised) June 7, 2001     

Selective Iodination of Benzylic Alcohols with KI/H<Subscript>2</Subscript>SO<Subscript>4</Subscript> Supported on Natural Kaolinitic Clay Under Microwave Irradiation

Summary.  Benzylic alcohols are selectively converted into their corresponding iodides using KI/H₂SO₄ supported on natural kaolinitic clay and microwaves. Received August 20, 2001. Accepted (revised) September 18, 2001     

Dimerization of Acetylenic Amides

Summary.  Dimers of substituted acetylenic amides were obtained when triethylamine was used as refluxing solvent and acid acceptor instead of pyridine in the reaction of substituted acetylenic amides with triphosgene. Unsubstituted acetylenic amides resulted in the corresponding quinazolinone. Received October 22, 2001. Accepted (revised) November 22, 2001     

Vinylphosphonium Salt Mediated Facile Synthesis of Trialkyl 4-(2-Quinolyl)-1-cyclobutene-1,2,3-tricarboxylates and Dialkyl 3-Ethoxy-4-oxo-5-(2-(1H)-quinolinylidene)-2-cyclopentene-1,2-dicarboxylates

Summary.  The reactive 1:1 intermediate produced in the reaction between dialkyl acetylenedicarboxylates and triphenylphosphine was trapped by ethyl 3-(1,2-dihydroquinoline-2-ylidene)-pyruvate to yield the isomeric dialkyl 3-ethoxy-4-oxo-5-(2-(1H)-quinolinylidene)-2-cyclopentene-1,2-dicarboxylates and trialkyl 4-(2-quinolyl)-1-cyclobutene-1,2,3-tricarboxylates in nearly 4:1 ratio. Received April 3, 2001. Accepted (revised) May 22, 2001     

Solid State Desemicarbazonation on Clayfen Under Microwave Irradiation

Summary.  A new, efficient, and environmentally benign method for the cleavage of semicarbazones has been achieved by a simple reaction of semicarbazones with clayfen under microwave irradiation. Received January 4, 2001. Accepted (revised) March 1, 2001     

Convenient Synthesis of 6H-[1,2,4,5]Tetrazino[3,2-b]quinazolin-6-ones

Summary.  The reaction of 3-amino-2-thioxo-4(1H)-quinazolinone or its 2-methylthio derivative with hydrazonoyl halides in the presence of ethanol and triethylamine affords 6H-[1,2,4,5]tetrazino[3, 2-b]quinazolin-6-ones. Received January 2, 2001. Accepted (revised) April 11, 2001     

Zinc-Promoted Reduction of 1,2-Diketones: A Simple, Efficient, and Mild Approach to a-Hydroxy Ketones

Summary.  1,2-Diketones were readily converted to α-hydroxy ketones in high to excellent yields using zinc in saturated ammonium chloride solution. Received June 7, 2001. Accepted (revised) August 7, 2001     

Thermochromism and Solvatochromism in Solution

Summary.  The thermochromic behaviour of various coordination compounds in solution is discussed, with a special focus on cyclic diamine chelates. Thermally induced spin-crossover phenomena of iron(II) complexes are also considered. The solvatochromic behaviour of mixed-ligand complexes is presented in detail. Received April 2, 2001. Accepted (revised) April 19, 2001     

Solid State Cleavage of Semicarbazones with Cerium Ammonium Nitrate Supported by Wet Alumina

Summary.  Cerium ammonium nitrate on wet alumina rapidly regenerates carbonyl compounds from their corresponding semicarbazone derivatives under solvent-free conditions; the process is expedited by microwave irradiation. Received April 25, 2001. Accepted (revised) July 9, 2001     

Chemoselective Protection of Hydroxyl Groups and Deprotection of Silyl Ethers

Summary.  Trimethylsilylation of alcohols and phenols is carried out using hexamethyldisilazane and LiClO₄ under microwave irradiation and neutral conditions. The deprotection of silyl ethers is carried out similarly using natural kaolinitic clay and a few drops of water. Received March 1, 2001. Accepted (revised) April 17, 2001     

Trifluoroacetic Anhydride Mediated Oxidative Functionalization of Some 2-Dimethylaminoethyl-Substituted Indoles

Summary.  2′-Dimethylamino-1′-trifluoroacetyl-2-vinylindole derivatives were prepared by trifluoroacetic anhydride assisted oxidation. Received July 20, 2001. Accepted (revised) September 24, 2001     

Synthesis, Characterization, and Biological Activity of n-Tributyltin Derivatives of Pharmaceutically Active Carboxylates

Summary.  Tributyltin(IV) derivatives of six different pharmaceutically active carboxylates were synthesized. The complexes were characterized by different analytical techniques (elemental analysis; infrared, NMR, and mass spectroscopy). ¹¹⁹Sn NMR data were also recorded in six different coordinating and non-coordinating solvents. The antibacterial activities of the compounds were tested using ten different bacteria relative to the reference drugs ampicillin and cephalexin. Received September 20, 2001. Accepted (revised) December 6, 2001     

Synthesis and Structure of O-silylated 2-Polyfluoroacyl-cycloalkanones

Summary.  2-Acyl-cycloalkanones containing polyfluoroalkyl groups react with dichlorodimethylsilane to form the corresponding heterocyclic bis-enol derivatives. The reaction of 2-polyfluoroacyl-cycloalkanones with chlorotrimethylsilane leads to mixtures of the corresponding (Z)-configured O-silylethers. The silatropy process in this case is slow on the NMR time scale. Received February 26, 2001. Accepted (revised) March 27, 2001     

Minor Alicyclic Diterpene Acidsfrom Conyza incana

Summary.  The reinvestigation of the CH₂Cl₂ extract of the aerial parts of Conyza incana led to the isolation of three minor alicyclic diterpene acids. The structures of the new compounds were established by a combination of spectroscopic methods. Received February 20, 2001. Accepted (revised) March 27, 2001     

2-Phenyl-4-quinolinone Alkaloids from Casimiroa edulis Llave et Lex (Rutaceae)

Summary.  Three new 4-quinolinone alkaloids (5,6-dimethoxy-2-(3-methoxyphenyl)-1H-quinolin-4-one, 5,6-dimethoxy-2-(3,4-dimethoxyphenyl)-1H-quinolin-4-one, 5,6-dimethoxy-2-(2,5,6-trimethoxyphenyl)-1H-quinolin-4-one) were isolated from the leaves of Casimiroa edulis Llave et Lex (Rutaceae) cultivated in Egypt. Their structures were determined by UV/Vis, IR, ¹H and ¹³C NMR, and EI mass spectroscopy. The alkaloids were also detected in the kernels of the seeds. Received May 28, 2001. Accepted (revised) July 24, 2001     

Microwave Assisted Mannich Reaction of Terminal Alkynes on Alumina

Summary.  Terminal alkynes, secondary amines, and formaldehyde undergo a Mannich reaction at room temperature in the presence of CuCl on Al₂O₃ without any organic solvent as reaction medium. The reaction can be promoted by microwave irradiation and is complete within one minute. Received May 2, 2001. Accepted (revised) June 25, 2001     

Trigonal B2O3 with Higher Space-Group Symmetry: Results of a Reevaluation

Summary.  A new crystal structure refinement based on published X-ray diffraction data [1] of the normal pressure modification of B₂O₃ (B₂O₃ form I) shows that the correct space group is (152) P3₁21 instead of (144) P3₁ within limits of error. Received May 28, 2001. Accepted (revised) July 16, 2001