- Preparation of Mono-/Difluorinated Hydrocarbon Compounds
-
Mono- or difluorinated hydrocarbon compounds are prepared from an alcohol or a carbonylated compound by reacting one of these with a fluorinating reagent, optionally in the presence of a base, the fluorinating agent comprising a pyridinium reactant having the following formula (F), wherein R0 is an alkyl or cycloalkyl radical:
- -
-
Page/Page column 7-8
(2009/09/28)
-
- Substituted pyridine or piperidine compounds
-
The invention relates to a compound of formula (I): wherein:A represents pyridine, pyridinium or piperidineR1, R2, R3 and R4 are as defined in the descriptionR5 represents hydrogen, a nitrogen-containing heterocycle or a group of R6 represents hydrogen or linear or branched (C1-C6)alkyl.and medicinal products containing the same which are useful in treating pain or deficiencies in memory.
- -
-
-
- Pseudo Vilsmeier reagents a new protocol for regiospecific C-C bond formation in pyridines
-
2-Fluoro- and 2,6-difluoropyridine are readily quaternised with methyl p-toluenesulfonate and methyl triflate respectively. These salts readily undergo substitution of fluorine by enamines, the difluoro-derivatives being capable of specific mono- or disubstitution in a symmetrical or unsymmetrical manner. The products reduced to give keto-1, 2, 3, 6-tetrahydropyridines, can be hydrosed to the corresponding ketopyridines or hydrogenated to give ketopiperidines.
- Yu, Chu-Yi,Taylor, David L.,Meth-Cohn, Otto
-
p. 6661 - 6664
(2007/10/03)
-
- C-Glycoside Syntheses. 1. Glycosyl Cyanides and Isocyanides from Glycosyl Fluorides with Full Acetal Protection
-
2,3:5,6-Di-O-isopropylidenemannofuranose, 2,3:4,6-di-O-isopropylidenemannopyranose, and 2,3,4,6-tetra-O-benzylglucopyranose each have been converted with 2-fluoro-1-methylpyridinium tosylate into anomerically pure pairs of glycosyl fluorides.Reaction of each anomeric mannopyranosyl and mannofuranosyl fluoride with Et2AlCN in THF gave only the two (four component) anomeric mixtures of mannopyranosyl, respectively mannofuranosyl cyanides and isocyanides.The pyranosidic four component mixture (α-CN, α-NC, β-CN, and β-NC) was completely separated by a combination of flash chromatography, crystallization, and/or preparative HPLC to give the individual components; in the furanose series, only the crystalline two component mixture of α-furano cyanide and isocyanide could not be resolved.Isocyanides show two absorption maxima in their UV spectra (195 and 230 nm) while cyanides show only the first.Cyanides, being C-glycosides, char more slowly on heated TLC plates than isocyanides.
- Drew, Kenneth N.,Gross, Paul H.
-
p. 509 - 513
(2007/10/02)
-
- Method for preparing pharmacologically active cyanoguanidine derivative
-
A pharmacologically active cyanoguanidine derivative, generally referred to as cimetidine, is prepared by causing 4-methyl-5-hydroxymethylimidazole or a salt thereof to react with 2-substituted-1-methyl pyridinium salt and then causing the intermediate reaction product to react with N-cyano-N'-methyl-N"-(2-melcaptoethyl)-guanidine. The initial and subsequent reactions are carried out at room temperature under atmospheric pressure, using one and the same reaction vessel. No isolation of the intermediate reaction product resulting from the first reaction is required preparatory to the subsequent reaction. The recovery of the final intended product is carried out without using a column chromatography.
- -
-
-