114497-93-7Relevant academic research and scientific papers
PYRIDINE ASSISTED OXIDATIONS OF ALCOHOLS TO CARBONYL COMPOUNDS BY MEANS OF 3-CARBOXYPYRIDINIUM DICHROMATE (NDC) REAGENT.
Cossio, Fernando P.,Lopez, Concepcion M.,Palomo, Claudio
, p. 3963 - 3974 (2007/10/02)
3-carboxypyridinium dichromate (NDC), readly prepareted from nicotinic acid and chromium trioxide, is an efficient reagent for the oxidation of alcohols into carbonyl compounds in the presence of pyridine.The optimum molar ratio substrate:reagent:pyridine to ensure complete oxidation of starting material in a short reaction time was found 1:2.5:20 respectlively.A brief compouison between this reagent and pyridinium dichromate (PDC) is made.In contrast to the PDC reagent, NDC allows selective oxidation between benzylic alcohols and aliphatic alcohols.The NDC-pyridine system has been successfully extended to the oxidation of N-(2-hidroxy-2-phenyl or 2-methylethyl)-β-lactams into their corresponding carbonyl compounds as N-H azetidin-2-one precursor.In contrast, primary N-(2-hydroxyethyl)-β-lactams upon treatment with this reagent system afforded N-formylazetidin-2-ones.The influence of pyridine in oxidations by means of NDC is further shown in the conversion of hydroquinones into quinones.Another interesting feature associated with the use of this reagent is the ease of purification of the final products.
SYNTHETIC APPLICATIONS OF CHROMIUM(VI) REAGENTS IN COMBINATION WITH CHLOROTRIMETHYLSILANE
Cossio, Fernando P.,Aizpurua, Jesus M.,Palomo, Claudio
, p. 225 - 231 (2007/10/02)
The synthetic utility of chromium(VI) reagents together with chlorotrimethylsilane, as new oxidizing systems, is described.Pyridinium dichromate (PDC) in combination with chlorotrimethylsilane oxidizes tert-butyldimethylsilyl ethers in good to excellent yields.Trimethylsilyl chlorochromate, a new chromium(VI) reagent, also was found efficient for this oxidative-deprotection method.These reagents were applied to the oxidation of some N-(2-phenyl-2-hydroxyethyl)azetidin-2-ones as well as N-(2-phenyl-2-trialkylsiloxy)azetidin-2-ones into their corresponding carbonyl compounds, key intermediates for N-unsubstituted β-lactams.Oxidation of hydroquinones and protected trialkylsilyl hydroquinones was also described.Protection of hydroquinones by means of the tert-butyldimethylsilyl group was achieved by using the readily available tert-butyldimethylchlorosilane (TBDMCS) and 1,8-diazabicycloundec-7-ene (DBU) as base, which avoids the use of sophisticated and (or) sensitive reagents.
TRIPHENYLPHOSPHINE DIBROMIDE AND DIMETHYLSULFIDE DIBROMIDE AS VERSATILE REAGENTS FOR BETA-LACTAM SYNTHESIS
Cossio, Fernando P.,Ganboa, Inaki,Palomo, Claudio
, p. 3041 - 3044 (2007/10/02)
Triphenylphosphine dibromide and dimethylsulfide dibromide are efficient reagents for the direct synthesis of beta-lactams from carboxylic acids and imines avoiding the use of acid halides as starting materials.Synthesis of 4-imino-beta-lactams are also briefly described.A potential synthesis of N-unsubstituted beta-lactams is made.
STEREOSELECTIVE ANNELATION OF TRIMETHYLSILOXYACETIC ACIDS AND IMINES INTO 3-HYDROXY-β-LACTAMS
Cossio, Fernando P.,Palomo, Claudio
, p. 4239 - 4242 (2007/10/02)
Stereoselective synthesis of variously substituted 3-hydroxy-β-lactams can be achieved by the annelation of Schiff bases with trimethylsiloxyacetic acids promoted by phenyl dichlorophosphate reagent.A potential synthesis of N-unsubstituted β-lactams is ma
3-CARBOXYPYRIDINIUM DICHROMATE (NDC) AND 4-CARBOXYPYRIDINIUM DICHROMATE (INDC). TWO NEW MILD, STABLE, EFFICIENT AND INEXPENSIVE CHROMIUM (VI) OXIDATION REAGENTS
Lopez, C.,Gonzalez, A.,Cossio, F. P.,Palomo, C.
, p. 1197 - 1212 (2007/10/02)
Two mild new chromium (VI) reagents derived from nicotinic acid and isonicotinic acid are described.Nicotinium dichromate (NDC) and isonicotinium dichromate (INDC) oxidize alcohols into carbonyl compounds, mercaptanes into disulfides and hydroquinones into quinones.Oxidation of polynuclear aromatic hydrocarbons is made.Pyridine assisted oxidations by means of these reagents are also described.
