Regeneration of Carbonyl Compounds by Oxidative Cleavage of Carbon-Nitrogen Double Bonds With Molecular Oxygen in the Presence of Copper(i) Chloride/Kieselghur as Catalyst

Protection (and Deprotection) of Functional Groups in Organic Synthesis by Heterogeneous Catalysis

“…Silica gel has been more extensively employed than clays and zeolites as heterogeneous support in performing oxidative deprotection of nitrogenous derivatives. A wide number of oxidizing reagents, namely nitrates, 276,224 chromates, [277][278][279] persul- fates, 280,281 iodates, 282 chlorides/O 2 , 283 and perchlorates, 284 were reported to be effective in performing the cleavage. In many cases, by using microwave irradiation, the deprotection reactions occurred faster and cleaner; [285][286][287][288][289][290][291][292][293][294] in fact, it has been reported that silica gel, in contrast to other cheap solid materials, is a good microwave conductor.…”

Deprotection of oximes, imines, and azines to the corresponding carbonyls using Cu-nanoparticles on cellulose template as green reusable catalyst

“…There are numerous methodologies reported for the deprotection of oximes and related compounds. 1,8 The classical method for the cleavage of oximes to carbonyls is acid hydrolysis, 9 although many other reagents, such as pyridinium chlorochromate (PCC) and related Cr(VI) compounds, 10 KMnO 4 / alumina, 11 trimethylphosphine and 2,2 0 -dipyridyl diselenide, 12 vanadomolybdophosphate (H 6 PMo 9 V 3 O 40 ), 13 mixed metal oxide CeO 2 -ZrO 2 , 14 FeCl 3 /TEMPO, 15 iron(III) porphyrin complex, 16 gaseous NO 2 , 17 Cu(I) chloride/kieselghur, 18 CuCl 2 , 2H 2 O, 19 mixed (Fe 2+ and Cu 2+ ) double metal hexacyanocobaltates, 20 platinum(II) terpyridyl acetylide complex/O 2 /hn, 21 TiO 2 /mesoporous silica, 22 cobalt(II) phthalocyanine/ionic liquid, 23 Au/CeO 2 , 24 I 2 /water, 25 2-nitro-4,5-dichloropyridazin-3(2H)-one, 26 and NaNO 2 , 27 have been also reported. Most of these methods are considerably efficient and produce good yields; however, they suffer from one or more serious drawbacks (Table 1), such as requiring the use of strong Lewis and Bronsted acids, 9 use of costly and hazardous metal/ligands (i.e., Mn, Cr, Ti, Au, and Pt), 10-16,20-24 use of toxic solvents, difficulty in catalyst/ product separation, problems associated with waste disposal, necessity of robust reaction conditions, generation of over-oxidized products, and long reaction time.…”

“…There are two different mechanisms reported for the Cucatalyzed deprotection of oximes, imines, and azines. 18,19 While oxidative deoximation is proposed for Cu(I) promoted reactions, 18 in the case of Cu(II), 19 it is only the co-ordination with nitrogen that increases the polarity of the C]N and leads to nucleophilic attack by water. In the current catalytic system, there is a mixture of Cu(0) and Cu(I).…”

An efficient approach to deoximation using hexachlorodisilane under mild conditions

“…Since oximes are prepared from a variety of basic organic compounds such as primary aliphatic amines [8], olefins [9], esters [10], nitriles [10], nitro compounds [11], and alcohols [12], regeneration of carbonyl compounds from oximes may be a convenient alternative method for the preparation of either aldehydes or ketones. Thus far, various deoximation methods based on acid-catalyzed hydrolysis [13][14][15][16], reductive cleavage [17], oxidative cleavage [18][19][20][21][22][23][24][25][26][27][28], and photosensitized oxidative deprotection [29][30][31] have been developed. However, these methods involve either highly poisonous or dangerous reagents, as well as expensive or difficultly accessible metal catalysts.…”