Direct conversion of oximes and hydrazones into their ketones with dinitrogen tetroxide

Kneading Ball‐Milling and Stoichiometric Melts for the Quantitative Derivatization of Carbonyl Compounds with Gas–Solid Recovery

“…[35] On the other hand, 65-90 % yields of compounds 1 j,v,z were reported upon reaction of 5 j,v,z with N 2 O 4 at À35 or À40 8C in CH 3 CN or THF. [15] The present solvent-free reactions with quantitative formation of aldehydes are different for various reasons. It is of particular importance that we apply the highest possible concentration of NO 2 without solvent deactivation, so that radical intermediates are rapidly trapped by NO 2 .…”

“…The quantitative formation of 1 is, however, obtained upon treatment with water by hydrolytic workup under acidic conditions that cannot be avoided even though a stoichiometric amount of waste is produced upon separation with heptane and water that takes up the by-products of hydrolysis. Therefore, the proposed mechanism (Scheme 6) involves the addition of NO 2 to the C=N bond of the oxime 5, followed by hydrogen transfer of 8 to give 9 with spin highly concentrated in the NHÀO bond, and rapid radical trapping by NO 2 to give 10, a very labile material that can be thought to decompose with [29] 90 Chromic acid-SiO 2 , CH 2 Cl 2 [30] 83 Tungstate sulfuric acid/NaNO 2 , CH 2 Cl 2 , RT [31] 93 Poly-[4-vinyl-N,N-dichlorobenzensulfonamide], CCl 4 , 5 h [32] 92 N 2 O 4 , THF, À35 8C, 10 min [15] 65 Surfactant/I 2 /water, 5 h [33] www.chemsuschem.org liberation of N 2 O and to many other products under various conditions. It will, however, readily hydrolyze on contact with water without liberating N 2 O.…”

“…Also, the use of N 2 O 4 at À40 8C in dangerous aprotic solvents such as CH 3 CN, THF, CHCl 3 , or CCl 4 for the deprotection of oximes and hydrazones afforded the parent carbonyls only with 65-95 % yield. [15] We report herein quantitative syntheses under solvent-free conditions [16][17][18][19] that provide superior results by kneading ball-milling or stoichiometric melt reaction, and the deprotection of the carbonyl derivatives to isolate the parent carbonyl compounds simply with gaseous NO 2 . All of these quantitative reactions avoid the production of dangerous wastes.…”

Product Selectivity in Solar Photocatalytic Dehydrazonation of Aromatic Hydrazones by TiO2-Based Catalysts

“…[1][2][3] There has been great interest in the development of mild techniques for the conversion of oximes into their corresponding carbonyl compounds. [4,5] A number of methods have been developed for the regeneration of carbonyl compounds from hydrazones, [6][7][8] but most of these methods suffer some disadvantages such as large reaction time, higher reflux temperature, difficulties in isolation of products and low yield. The classical method of regeneration by acid hydrolysis is not suitable for acid sensitive compounds.…”

Deprotection Chemistry Mediated by ZrOCl2 · 8H2O: An Efficient, Mild, and Green Method for the Conversion of Oximes to Carbonyl Compounds in Aqueous Acetone

“…[5] In addition, oximes may be used as intermediates for the preparation of amides by Beckmann rearrangement. [6] These requirements and demands for oximes has inspired the development of several deoximation reagents such as trimethylammonium chlorochromate, [7] dinitrogen tetroxide, [8] pyridinium chloroformate, [9] trimethylsilyl chloroformate, [10] titanium silicate-1, [11] zirconium sulfophenyl phosphonate, [12] and N-haloamides. [13] Photosensitized reaction also finds application in the regeneration of carbonyl compounds from oximes.…”