Papers by Igor Kolomitsyn
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
ChemInform, Feb 4, 2003
ates.-Acyltrifluoroacetyl peroxides, generated in situ from carboxylic peracids (I) and trifluoro... more ates.-Acyltrifluoroacetyl peroxides, generated in situ from carboxylic peracids (I) and trifluoroacetyl anhydride (II), undergo spontaneous decomposition into alkyl trifluoroacetates (III). Interestingly, acetyltrifluoroacetyl peroxide (V) is found to be stable at room temperature.
Microporous and Mesoporous Materials, 2002
A series of carbonate layered double hydroxides (LDHs) with different Mg 2þ /M 3þ (M 3þ ¼ Al, Ga)... more A series of carbonate layered double hydroxides (LDHs) with different Mg 2þ /M 3þ (M 3þ ¼ Al, Ga) atomic ratios were prepared by the co-precipitation method. Extensive characterization evidenced the formation of well-crystallized hydrotalcite-like structures with homogeneously distributed M 3þ cations for all samples. The mixed oxides obtained after calcination at 773-873 K of these LDHs, which can be considered as non-equilibrium oxide solutions, are active and highly selective catalysts in the production of several aromatic amides under mild reaction conditions by means of nitrile hydrolysis in the presence of H 2 O 2. High activities were found for Mg-Al LDH with an Al=ðAl þ MgÞ molar ratio of 0.25, for Mg-Al, Ga LDH, both calcined at 773 K, and for Mg-Ga sample with Ga=ðGa þ MgÞ ratio of 0.12 calcined at 873 K. The base properties of the mixed oxides, being strongly dependent on the LDH chemical composition and calcination temperature, are of key importance for the catalyst activity in nitrile hydrolysis. Brønsted basic sites of moderate strength are formed at the start of the reaction upon interaction of the O 2À species with water. These Brønsted basic sites are considered the most likely active centers.The basicity was evaluated from benzoic acid titration evaluated of partially hydrated catalysts. A good correlation was obtained between the basicity and catalyst activity. Using several benzonitrile ring substituted derivatives, it was shown that WibergÕs classical reaction mechanism is also operative when calcined LDH catalysts are used in nitrile hydrolysis. The catalysts can be regenerated by calcination achieving the same nitrile conversion as fresh catalysts.
Natural Product Communications, 2007
The chemical content of outer birch bark extractive from the North American birches Betula papyri... more The chemical content of outer birch bark extractive from the North American birches Betula papyrifera Marshall (paper birch) and B. neoalaskana Sargent (Alaskan paper birch) has been evaluated by GC/MS, HPLC and NMR spectroscopy. The comparative antiproliferative activity of the extractive and major triterpenoid components was studied using a number of human and murine malignant (P19, N2/D1, K1735-M2, PC-3 and CaOV3) and normal (BJ) cell lines. Betulin 3-caffeate was found to exhibit the highest antiproliferative activity among all triterpenoid components, including betulinic acid. Synthesis of betulin 3-caffeate from betulin has been developed.
ChemInform, 2005
ABSTRACT For Abstract see ChemInform Abstract in Full Text.
Tetrahedron Letters, 2002
ates.-Acyltrifluoroacetyl peroxides, generated in situ from carboxylic peracids (I) and trifluoro... more ates.-Acyltrifluoroacetyl peroxides, generated in situ from carboxylic peracids (I) and trifluoroacetyl anhydride (II), undergo spontaneous decomposition into alkyl trifluoroacetates (III). Interestingly, acetyltrifluoroacetyl peroxide (V) is found to be stable at room temperature.
Organic Letters, 2001
A new catalytic method for synthesis of bis(perfluoroacyl) peroxides (BPFAP) was elaborated by us... more A new catalytic method for synthesis of bis(perfluoroacyl) peroxides (BPFAP) was elaborated by using hydrogen peroxide and perfluoroacyl anhydrides. The desired BPFAP were formed quantitatively in situ when perfluoroacyl anhydride was mixed with hydrogen peroxide (ratio > or = 2:1) in the presence of a catalytic amount of the carboxylate R(f)COO-M+. The essentially irreversible character of this process was shown experimentally and supported on the basis of DFT calculations. The synthesis of new acetyltrifluoroacetyl peroxides is also described. Reaction: see text.
The Journal of Organic Chemistry, 2001
Rearrangement of 4-methylhomoadamantan-4-ol (1) with trifluoroperacetic acid (TFPAA) in trifluoro... more Rearrangement of 4-methylhomoadamantan-4-ol (1) with trifluoroperacetic acid (TFPAA) in trifluoroacetic acid (TFAA) proceeds with the formation of 4-oxahomoadamantane 6 and its derivatives (4 and 5). 2-exo-Hydroxy-4-oxahomoadamantane (5) and 6 were identified as a result of consecutive O-insertion Criegee rearrangement processes. The absence of methyl trifluoroacetate and methyl trifluoroperacetate among the reaction products, as well as the presence of acetyltrifluoroacetyl peroxide, is consistent with a double rather that a triple oxygen insertion during the course of the Criegee reaction. A mechanism involving initial Criegee rearrangement followed by a Baeyer-Villiger reaction is also excluded by kinetic considerations. The parallel formation of 4-ethyl-3-oxahomoadamantan-2-one (4) was determined to be the result of 4-methylhomoadmantan-4-ol (3) dehydration, with subsequent epoxidation of 4-methylhomoadamant-4-ene (32) to 4,5-epoxy-4-methylhomoadamantane (33), acid-catalyzed isomerization of 33 to 3-methylhomoadamantan-2-one (34), and Baeyer-Villiger oxidation to 3-methyl-5-oxabishomoadamantan-6-one (35). This sequence of reactions was followed by the acid-catalyzed isomerization to the final product 4. The proposed mechanisms for these transformations are discussed on the basis of model experiments and supporting density functional theory (DFT) calculations.
The Journal of Organic Chemistry, 2000
Arkivoc, 2005
Recent achievements in the use of trifluoroperacetic acid (TFPAA) in consecutive Criegee rearrang... more Recent achievements in the use of trifluoroperacetic acid (TFPAA) in consecutive Criegee rearrangement are covered in this review. Consecutive Criegee rearrangement promoted by TFPAA represents a new approach to this classic method in organic chemistry. The concept of selective double and triple O-insertion is described through the analysis of kinetic data, the overview of synthetic examples and studies of the reaction mechanisms. TFPAA in trifluoroacetic acid (TFAA) media is introduced as a specific reagent for consecutive Criegee rearrangement and for stable carboxonium ion generation. Heterolytic decarboxylation and bisperfluoroacyl peroxide synthesis are discussed as miscellaneous and useful reactions.
Angewandte Chemie, 1998
Die CH-Bindungen aliphatischer Kohlenwasserstoffe[1] können mit elektronisch ungesättigten Überga... more Die CH-Bindungen aliphatischer Kohlenwasserstoffe[1] können mit elektronisch ungesättigten Übergangsmetallkom-plexen,[2±6] Supersäuren[32] oder durch enzymatische Prozes-se[7, 8] aktiviert werden. Hier möchten wir nun eine äuūerst ungewöhnliche Methode zur CH-...
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Papers by Igor Kolomitsyn