Synthesis of ketones by hydrolysis, deprotection, or oxidation
Oximes of various aldehydes and ketones can be converted to the corresponding carbonyl compounds at room temperature in excellent yields with 2-iodylbenzoic acid in water in the presence of β-cyclodextrin.
N. S. Krishnaveni, K. Surendra, Y. V. D. Nageswar, K. R. Rao, Synthesis, 2003, 1968-1969.
Carbonyl compounds were obtained in very good yields after treatment of oximes with 2 molar equivalent of CuCl2 • 2 H2O at reflux in acetonitrile and water (4:1). In addition, cupric salt was readily recovered in an almost quantitative yield via the complete precipitation of Cu(OH)2 • 2 H2O.
N. Quan, X.-X. Shi, L.-D. Nie, J. Dong, R.-H. Zhu, Synlett, 2011, 1028-1032.
N-bromosaccharin is an efficient reagent for the oxidative cleavage of oximes to the corresponding aldehydes and ketones under microwave irradiation in a domestic microwave oven. This procedure features short reaction times, high chemoselectivity (no over-oxidation), easy work-up and high yields.
A. Khazaei, A. A. Manesh, Synthesis, 2004, 1739-1740.
A simple, mild and efficient procedure cleaves a wide range of ketoximes and aldoximes to the corresponding carbonyl compounds in an aqueous medium using catalytic amounts of potassium bromide and ammonium heptamolybdate tetrahydrate in combination with hydrogen peroxide.
N. C. Ganguly, S. K. Barik, Synthesis, 2008, 425-428.
I2 catalyzes the deprotection of oximes and imines to the corresponding carbonyl compounds under neutral conditions in a water/surfactant system at 25-40°C in high yields.
P. Gogoi, P. Hazarika, D. Konwar, J. Org. Chem., 2005, 70, 1934-1936.
Various aliphatic and aromatic oximes were converted to their corresponding aldehydes and ketones in good to excellent yields in the presence of 2-nitro-4,5-dichloropyridazin-3(2H)-one under microwave irradiation. It is noteworthy that the reaction is conducted under neutral, mild, and eco-friendly condition.
B. R. Kim, H.-G. Lee, E. J. Kim, S.-G. Lee, Y.-J. Yoon, J. Org. Chem., 2010, 75, 484-486.
A rapid and efficient oxidative deamination of various α-aminophosphonates allows the synthesis of α-ketophosphonates using ZnCr2O7 • 3 H2O under solvent-free conditions at room temperature. This method is also applicable to the rapid and highly selective oxidation of various amines to aldehydes and ketones in very good yields.
S. Sobhani, M. F. Maleki, Synlett, 2010, 382-386.
α-Keto esters can be prepared via Mannich addition of ethyl diazoacetate to imines followed by oxidation of the diazo group with Oxone. Implementation of a recently developed dynamic kinetic resolution of β-substituted-α-keto esters via Ru(II)-catalyzed asymmetric transfer hydrogenation provides enantioenriched anti-α-hydroxy-β-amino acid derivatives in high diastereo- and enantioselectivity.
C. G. Goodman, D. T. Do, J. S. Johnson, Org. Lett., 2013, 15, 2446-2449.
A transition-metal-free coupling of aldehydes and ketones with geminal bis(boron) building blocks provides homologated carbonyl compounds upon oxidation. Aldehydes with an enolizable stereogenic center undergo this reaction with complete retention of stereochemistry.
T. C. Stephens, G. Pattison, Org. Lett., 2017, 19, 3498-3501.
An efficient and convenient procedure has been developed for the hydrolysis of thioacetals/thioketals to the corresponding carbonyl compounds in excellent yields with o-iodoxybenzoic acid (IBX) in presence of β-cyclodextrin (β-CD) in water under neutral conditions at room temperature.
N. S. Krishnaveni, K. Surendra, Y. V. D. Nageswar, K. R. Rao, Synthesis, 2003, 2295-2297.
A number of new reactions of IBX with heteroatom-containing substrates were discovered and their utility was demonstrated. IBX was used for the generation of imines from secondary amines in notably high yields, for the oxidative aromatization of nitrogen heterocycles and for the cleavage of dithianes.
K. C. Nicolaou, C. J. N. Mathison, T. Montagnon, Angew. Chem. Int. Ed., 2003, 42, 4077-4082.
In the presence of hydrogen peroxide and trimethylsilyl chloride, thiocarbonyls desulfurize to the corresponding carbonyls in short reaction times with no side reactions and excellent selectivity. This process is a safe, operationally simple, and environmentally benign alternative for the desulfurization of thiocarbonyls.
K. Bahrami, M. M. Khodaei, M. Tajik, Synthesis, 2010, 4282-4286.
Perchloric acid adsorbed on silica gel is an extremely efficient, inexpensive, and reusable catalyst for the protection of aldehydes and ketones and the subsequent deprotection. Acetalization was mostly carried out under solvent-free conditions with trialkyl orthoformates, but weakly electrophilic carbonyl compounds and substrates that can coordinate with the catalyst, required the corresponding alcohol as solvent.
R. Kumar, D. Kumar, A. K. Chakraborti, Synthesis, 2007, 299-303.
Er(OTf)3 is a very gentle Lewis acid catalyst in the chemoselective cleavage of alkyl and cyclic acetals and ketals at room temperature in wet nitromethane.
R. Dalpozzo, A. De Nino, L. Maiuolo, M. Nardi, A. Procopio, A. Tagarelli, Synthesis, 2004, 496-498.
Exo-3-furanylidenes and 3-pyranylidenes products having cis-2,5 and cis-2,6 substitution were synthesized from terminally substituted alkynyl alcohols with various aldehydes via Prins-type cyclization and trapping of the resulting vinyl cations as vinyl triflates in good yields. Vinyl triflates underwent a subsequent stereoselective hydrolysis to give the corresponding 3-acyl-substituted products.
S. N. Chavre, H. Choo, J. K. Lee, A. N. Pae, Y. Kim, Y. S. Cho, J. Org. Chem., 2008, 73, 7467-7471.
Silylated cyanohydrins of iodo-substituted aryl, heteroaryl, or cycloalkenyl ketones undergo an I/Mg-exchange using i-PrMgCl·LiCl. After subsequent reactions with electrophiles, a facile deprotection produces polyfunctional ketones in good overall yiels. An extension to aromatic iodoaldehydes is described.
C.-Y. Liu, H. Ren, P. Knochel, Org. Lett., 2006, 8, 617-629.
α,α-Disubstituted acetamides undergo oxidative mild, efficient, and general dehomologation to give one-carbon-shorter ketones when reacted with the hypervalent iodine reagent o-iodoxybenzoic acid (IBX) in combination with tetraethylammonium bromide (TEAB).
E. V. Bellale, D. S. Bhalarao, K. H. Chaudhari, K. G. Akamanchi, J. Org. Chem., 2008, 73, 9473-9475.
The use of alkali metal hydrides as reagents enables a mild, efficient protocol for the aerobic oxidative cleavage of C-C bonds in aldehydes. The method is applicable to a broad substrate range.
S. A. Shipilovskikh, A. E. Rubtsov, A. V Malkov, Org. Lett., 2017, 19, 6760-6762.
The visible-light mediated oxidative C-C bond cleavage of aldehydes has been achieved in good yields at ambient temperature and open to air using Ru(bpy)3Cl2 as the photoredox catalyst.
H. Sun, C. Yang, F. Gao, Z. Li, W. Xia, Org. Lett., 2013, 15, 624-627.
An electrochemical oxidative decarboxylation of wide range of disubstituted malonic acids leads to dimethoxy ketals in very good yields in the presence of NH3. Treatment of the crude reaction mixture after electrolysis with 1 M aq HCl enables the synthesis of ketones in a single vessel operation.
X. Ma, Y. Luo, S. Dochain, C. Mathot, I. E. Marko, Org. Lett., 2015, 17, 4690-4693.
A transition-metal-free oxidative C-C bond cleavage process for a broad range of ester and dicarbonyl compounds involves carbanion addition to nitrosobenzene and proceeds via fragmentation of a previously unobserved oxazetidin-4-one heterocycle.
J. N. Payette, H. Yamamoto, J. Am. Chem. Soc., 2008, 130, 12276-12278.
An efficient and mild fluorination of vinyl azides enables the synthesis of α-fluoroketones via a single-electron transfer (SET) and a subsequent fluorine atom transfer.
S.-W. Wu, F. Liu, Org. Lett., 2016, 18, 3642-3645.
N-Sulfonyl-1,2,3-triazoles react with water in the presence of a rhodium catalyst to produce α-amino ketones in high yield. This transformation formally achieves 1,2-aminohydroxylation of terminal alkynes in a regioselective fashion in combination with a copper(I)-catalyzed 1,3-dipolar cycloaddition with N-sulfonyl azides.
T. Miura, T. Biyajima, T. Fujii, M. Murakami, J. Am. Chem. Soc., 2012, 134, 194-196.