Synthesis of α-hydroxy ketones and aldehydes
Various terminal olefinic compounds are directly converted into the corresponding α-hydroxy ketones in good yields by potassium permanganate oxidation. The reaction is highly chemoselective in the presence of differently protected hydroxy groups.
C. Bonini, L. Chiummiento, M. Funicello, P. Lupattelli, M. Pullez, Eur. J. Org. Chem., 2006, 80-83.
I2-catalyzed oxo-acyloxylation of alkenes and enol ethers with carboxylic acids provides α-acyloxyketones and esters in high yields. This unprecedented regioselective oxidative process employs TBHP and Et3N in stoichiometric amounts under metal-free conditions in DMSO as solvent. α-Acyloxyketones can be converted in situ to monoprotected diol derivatives in excellent yields upon treatment with BH3ĚSMe2.
R. N. Reddi, P. K. Prasad, A. Sudalai, Org. Lett., 2014, 16, 5674-5677.
A direct, mild ketohydroxylation of various 1-aryl-1-alkenes with H2O2, catalyzed by the inexpensive 12-tungstophosphoric acid/cetylpyridinium chloride system, gave acyloins in good yields and high regioselectivies.
Y. Zhang, Z. Shen, J. Tang, Y. Zhang, L. Kong, Y. Zhang, Org. Biomol. Chem., 2006, 4, 1478-1482.
Cobalt bis(acetylacetonate) mediates hydrogen atom transfer to a broad range of functionalized alkenes. In situ oxidation of the resulting alkylradical intermediates, followed by hydrolysis, provides expedient access to ketones and esters. This method is compatible with a number of functional groups and provides a mild and practical alternative to the Tamao-Fleming oxidation of vinylsilanes and the Arndt-Eistert homologation.
X. Ma, S. B. Herzon, J. Org. Chem., 2016, 81, 8673-8695.
Phenyliodonium diacetate mediates a synthesis of α-oxygenated ketones from styrenes in the presence of molecular oxygen and N-hydroxyphthalimide or N-hydroxybenzotriazole under metal-free conditions. The present method is applicable for wide range of styrenes with various functional groups.
S. Samanta, R. R. Donthiri, C. Ravi, S. Adimurthy, J. Org. Chem., 2016, 81, 3457-3463.
The use of PhI(OAc)2 enables an efficient access to α,α′-diacetoxy ketones has from ethynylcarbinols. Glycerol derivatives can be easily synthesized in good yields via a one-pot reaction. A plausible mechanism is proposed.
Q.-R. Liu, C.-X. Pan, X.-P. Ma, D.-L. Mo, G.-F. Su, J. Org. Chem., 2015, 80, 6496-6501.
A highly enantioselective method for catalytic reductive coupling of alkynes and aldehydes afforded allylic alcohols with complete E/Z selectivity, generally >95:5 regioselectivity, and in up to 96% ee. In conjunction with ozonolysis, this process allows the enantioselective synthesis of α-hydroxy ketones.
K. M. Miller, W.-S. Huang, T. F. Jamison, J. Am. Chem. Soc., 2003, 125, 3442-3443.
IBX has been utilized for the oxidation of various epoxides and aziridines as their β-cyclodextrin complexes in water to afford α-hydroxyketones and α-aminoketones in good yields, respectively.
K. Surendra, N. S. Krishnaveni, M. A. Reddy, Y. V. D. Nageswar, K. R. Rao, J. Org. Chem., 2003, 68, 9119-9121.
A mild and efficient oxidation of alcohols with o-iodoxybenzoic acid (IBX) is catalyzed by β-cyclodextrin in a water/acetone mixture (86:14). Various alcohols were oxidized at room temperature in excellent yields.
K. Surendra, N. Srilakshmi Krishnaveni, M. Arjun Reddy, Y. V. D. Nageswar, K. Rama Rao, J. Org. Chem., 2003, 68, 2058-2059.
A two-step sequence of asymmetric dihydroxylation and regioselective monooxidation gave enantiopure α-hydroxy ketones (acyloins). The combination of RuCl3/Oxone/NaHCO3 was used in the first catalytic regioselective oxidation of vic-diols to α-ketols.
B. Plietker, Org. Lett., 2004, 6, 289-291.
A catalyst comprising of Ph3PAuCl and AgSbF6 efficiently hydrolyzes terminal alkyne groups of propargyl acetates in the absence of acid promoters at ambient temperature within a short time. Effective regioselective hydration is facilitated by the neighboring carbonyl group. Synthesis of actinopolymorphol B is achieved involving hydration of the propargyl acetate as the key step.
N. Ghosh, S. Nayak, A. K. Sahoo, J. Org. Chem., 2011, 76, 500-511.
Transformation of epoxides to β-alkoxy alcohols, acetonides, and α-alkoxy ketones is achieved by using molybdenum(VI) dichloride dioxide (MoO2Cl2) as a catalyst. Alcohol, aldehyde, oxime, tosyl, and tert-butyldimethylsilyl functional groups are tolerated during the methanolysis and acetonidation of the functionalized epoxides.
K. Jeyakumar, D. K. Chand, Synthesis, 2008, 807-819.
Grubbs' 2nd generation metathesis catalyst can be used in tandem olefin metathesis/oxidation protocols. These ruthenium-catalyzed processes provide access to cis-diols or α-hydroxy ketones from simple olefinic starting materials.
A. A. Scholte, M. H. An, M. L. Snapper, Org. Lett., 2006, 8, 4759-4762.