102488-27-7Relevant academic research and scientific papers
Experimental Evidence on the Formation of Highly Strained 6,7-Dihydroazeto[2,1-b]oxazol-3-ium Derivatives as Reactive Intermediates
Xie, Wenlai,Sun, Simin,Xu, Jiaxi
, (2022/01/31)
The formation of highly strained 6,7-dihydroazeto[2,1-b]oxazol-3-ium derivatives (4-oxa-1-azabicyclo[3.2.0]hepta-1(5),2-dien-1-ium) as reactive intermediates was observed through the treatment of N-2-aryl-2-oxoethylazetidin-2-ones with phosphorus oxychlor
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.
Synthesis of β-lactams from acetic acids and imines induced by phenyl dichlorophosphate reagent
Arrieta,Cossio,Palomo
, p. 1703 - 1712 (2007/10/02)
The development of a practical method for the preparation of vinylamino-β-lactams from Dane salts and Schiff bases is described. Among the reagents known to produce β-lactams from imines and acetic acids, only phenyl dichlorophosphate and 1-methyl-2-chloropyridinium iodide are suitable for the synthesis of vinylamino-β-lactams. Reaction of acetic acids with ethanolimine derivatives promoted by phenyl dichlorophosphate affords oxazolidines instead of β-lactams. Protection of the hydroxyl group as the trimethylsilyl ether in the starting Schiff bases provides a convenient route to the corresponding β-lactams instead of oxazolidines. Some observations on the scope of the method are made.
