Categories: C-O Bond Formation >
Synthesis of diols by dihydroxylation
A rhodium-catalyzed enantioselective syn addition of bis(catecholato)diboron to simple alkenes in the presence of (S)-Quinap provides enantioenriched 1,2-diols after subsequent oxidation. The substrate scope, the reaction mechanism, and competing pathways are discussed.
S. Trudeau, J. M. Morgan, M. Shrestha, J. P. Morken, J. Org. Chem., 2005, 70, 9538-9544.
Catalytic enantioselective diboration of alkenes is accomplished with readily available carbohydrate-derived catalysts via the intermediacy of 1,2-bonded diboronates.
L. Fang, L. Yan, F. Haeffner, J. P. Morken, J. Am. Chem. Soc., 2016, 138, 2508-2511.
A Pt-catalyzed enantioselective addition of bis(pinacolato)diboron to various terminal alkenes occurs in the presence of a readily available chiral phosphonite ligand. While oxidation of the intermediate 1,2-bis(boronate) ester provides a chiral 1,2-diol as the reaction product, homologation/oxidation furnishes a chiral 1,4-diol.
L. T. Kliman, S. N. Mlynarski, J. P. Morken, J. Am. Chem. Soc., 2009, 131, 13210-13211.
A catalytic enantioselective diboration of vinyl boronate esters furnishes chiral tris(boronates). Subsequent intermolecular or intramolecular deborylative alkylation occurs in a diastereoselective fashion.
J. R. Coombs, L. Zhang, J. P. Morken, J. Am. Chem. Soc., 2014, 136, 16140-16143.
An aerobic acetoxyhydroxylation of alkenes is cooperatively catalyzed by organic nitrite and palladium at room temperature using clean and cheap air as the sole oxidant. Various vicinal diols, diacetoxyalkanes, and dihalogenoalkanes have been synthesized.
X.-M. Chen, X.-S. Ning, Y.-B. Kang, Org. Lett., 2016, 18, 5368-5371.
A platinum-catalyzed hydrosilylation of arylacetylenes with trichlorosilane followed by a subsequent second hydrosilylation catalyzed by a chiral monophosphine-palladium complex and an oxidation with hydrogen peroxide gave 1-aryl-1,2-diols of high enantiomeric purity in high yields.
T. Shimada, K. Mukaide, A. Shinohara, J. W. Han, T. Hayashi, J. Am. Chem. Soc., 2002, 124, 1584-1585.
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 BH3ˇSMe2.
R. N. Reddi, P. K. Prasad, A. Sudalai, Org. Lett., 2014, 16, 5674-5677.
Aryl iodides are efficient catalysts in an organocatalytic syn diacetoxylation of alkenes. A broad range of substrates, including electron-rich as well as electron-deficient alkenes, furnish the desired products in very good yields with high diastereoselectivity.
W. Zhong, S. Liu, J. Yang, X. Meng, Z. Li, Org. Lett., 2012, 14, 3336-3339.
Addition of perfluoro-tert-butyl alcohol to a toluene solution of alkene and cyclopropyl malonoyl peroxide increases the rate of dihydroxylation product formation and the stereoselectivity observed, providing a simple and effective method for acceleration of this important class of reaction. Basic hydrolysis of the crude reaction mixture provides access to syn-diols in high yield and stereoselectivity.
S. Picon, M. Rawling, M. Campbell, N. C. O. Tomkinson, Org. Lett., 2012, 14, 6250-6253.
A clean and efficient and metal-free diacetoxylation reaction of alkenes using commercially available peroxyacids as the oxidants is catalyzed by triflic acid. This method enables also oxidative lactonizations of unsaturated carboxylic acids in good to high yields.
Y.-B. Kang, L. H. Gade, J. Org. Chem., 2012, 77, 1610-1615.
An improved protocol for the RuO4-catalyzed syn-dihydroxylation uses only 0.5 mol% catalyst under acidic conditions. Various olefins can be hydroxylated in good to excellent yields with only minor formation of side products.
B. Plietker, M. Niggemann, Org. Lett., 2003, 3353-3356.
Cyclopropyl malonoyl peroxide, which can be prepared in a single step from the commercially available diacid, enables an effective dihydroxylation of alkenes in the presence of water at 40°C. Alkaline hydrolysis of the resulting monoester leads to the corresponding diol. With 1,2-disubstituted alkenes, the reaction proceeds with syn selectivity.
J. C. Griffith, K. M. Jones, S. Picon, M. J. Rawling, B. M. Kariuki, M. Campbell, N. C. O. Tomkinson, J. Am. Chem. Soc., 2010, 132, 14410-14411.
Copper(I) or -(II) salts with weakly coordinating anions catalyze a mild diacetoxylation of olefins efficiently in the presence of PhI(OAc)2 as the oxidant. The reaction is effective for aryl, aryl alkyl, as well as aliphatic terminal and olefins forming the corresponding vicinal diacetoxy compounds in good yields. Internal olefins lead to syn/anti mixtures of up to 5.2.
J. Seayad, A. M. Seayad, C. L. L. Chai, Org. Lett., 2010, 12, 1412-1415.
A palladium-catalyzed diacetoxylation of alkenes in the presence of peracetic acid and acetic anhydride produces diacetates efficiently and diastereoselectively. Due to its mild conditions, this method is suitable for a broad range of substrates encompassing conjugated and nonconjugated olefins.
C. P. Park, J. H. Lee, K. S. Yoo, K. W. Jung, Org. Lett., 2010, 12, 2450-2452.
LiBr is an efficient catalyst for the dihydroxylation of alkenes to afford either syn or anti diols with excellent diastereoselectivity depending upon the use of NaIO4 or PhI(OAc)2 as the oxidants.
L. Emmanuvel, T. M. A. Shaikh, A. Sudalai, Org. Lett., 2005, 7, 5071-5074.
Selective syn and anti diacetoxylations of alkenes have been achieved using a PhI(OAc)2/BF3ˇOEt2 system in the presence and absence of water, respectively. A broad range of substrates including electron-deficient alkenes furnishes the desired products in good to excellent yields and diastereoselectivity. This novel methodology provides an alternative approach for the preparation of various 1,2-diols.
W. Zhong, J. Yang, X. Meng, Z. Li, J. Org. Chem., 2011, 76, 9997-10004.
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.
A clean and safe method for the dihydroxylation of alkenes under organic-solvent- and metal-free conditions was developed. The resin-supported sulfonic acid is easily recycled.
Y. Usui, K. Sato, M. Tanaka, Angew. Chem. Int. Ed., 2003, 42, 5623-5625.
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.
An efficient and economic procedure for the dihydroxylation of various olefin derivatives with commercial KMnO4 as the oxidant in the presence of a quaternary ammonium salt is suitable for large-scale production of cis-dihydroxy compounds, even those bearing primary and secondary alcohol groups, without overoxidation.
Z.-b. Luo, C. Zhao, J. Xie, H.-f. Lu, Synthesis, 2016, 48, 3696-3700.
A dioxygenation of alkenes using molecular oxygen and a simple, readily prepared hydroxamic acid derivative in th presence of a radical initiator offers an alternative to common dioxygenation processes catalyzed by precious transition metals. This transformation capitalizes on the unique reactivity profile of hydroxamic acid derivatives in radical-mediated alkene addition processes.
B. C. Giglio, V. A. Schmidt, E. J. Alexanian, J. Am. Chem. Soc., 2011, 133, 13320-13322.