Synthesis of (saturated) alcohols
Ionic liquids enhanced the nucleophilicity of water and reduced the formation of elimination products in the nucleophilic hydroxylation of alkyl halides. The reactivity of other nucleophiles such as alcohols, phenol, and acetic acid in an ionic liquid was also investigated.
D. W. Kim, D. J. Hong, J. W. Seo, H. S. Kim, H. K. Kim, C. E. Song, D. Y. Chi, J. Org. Chem., 2004, 69, 3186-3189.
Convenient methods for the preparation of stable and non-volatile mono- and dichloroborane adducts of dioxane from dioxane-BCl3 and NaBH4 in the presence of catalytic amounts of tri- or tetraglyme were developed. The dioxane-monochloroborane adduct hydroborates representative olefins cleanly and rapidly and lead to the corresponding alcohols in quantitative yields after oxidation.
J. V. B. Kanth, H. C. Brown, J. Org. Chem, 2001, 66, 5359-5365.
The use of Oxone allows the conversion of various aryl-, heteroaryl-, alkenyl-, and alkyltrifluoroborates into the corresponding oxidized products in excellent yields. This method tolerates a broad range of functional groups, and in secondary alkyl substrates it was demonstrated to be completely stereospecific.
G. A. Molander, L. N. Cavalcanti, J. Org. Chem., 2011, 76, 623-630.
The combination of sBuLi and TMEDA in CPME at -60 °C enables deprotonation of unactivated, chiral secondary dialkyl TIB esters. These carbanions were reacted with a range of neopentyl boronic esters which, after 1,2-metalate rearrangement and oxidation, gave a range of tertiary alcohols in high yield and high ee. Further functional group transformations of the tertiary boronic esters were demonstrated.
A. P. Pulis, D. J. Blair, E. Torres, V. K. Aggarwal, J. Am. Chem. Soc., 2013, 135, 16054-16057.
Using commercially available Ph3PAuCl and readily prepared, benign arylsilanes, a gold-catalyzed oxyarylation of alkenes proceeds smoothly in air. The oxidant, Selectfluor, not only facilitates entry to the Au(I/III) manifold but also provides a fluoride anion for silane activation, thereby avoiding the need for addition of a stoichiometric base.
L. T. Ball, M. Green G. C. Lloyd-Jones, C. A. Russel, Org. Lett., 2010, 12, 4724-4727.
An air-stable half-sandwich ruthenium complex is a highly active catalyst for the anti-Markovnikov reductive hydration of alkynes, involving the decarboxylation of formic acid, hydration of the alkyne, and hydrogenation of the intermediate aldehyde. A wide array of terminal alkynes are efficiently processed to linear alcohols using as little as 2 mol % of catalyst at ambient temperature.
M. Zeng, L. Li, S. B. Herzon, J. Am. Chem. Soc., 2014, 136, 7058-7067.
Two complementary dual catalytic systems enable a highly regioselective reductive hydration of terminal alkynes to yield branched or linear alcohols in very good yield. The method is compatible with terminal, di-, and trisubstituted alkenes. This reductive hydration constitutes a strategic surrogate to alkene oxyfunctionalization and may be of utility in multistep settings.
L. Li, S. B. Herzon, J. Am. Chem. Soc., 2012, 134, 17376-17378.
(Hydrido)silyl ethers, generated in situ by dehydrogenative coupling of tertiary alcohols with diethylsilane, undergo regioselective silylation at a primary C-H bond δ to the hydroxyl group in the presence of [(Xantphos)Rh(Cl)] as catalyst. Fleming-Tamao oxidation of the resulting 6-membered oxasilolanes provides 1,4-diols.
C. Karmel, B. Li, J. F. Hartwig, J. Am. Chem. Soc., 2018, 140, 1460-1470.
(NH4)2S2O8 mediates a metal-free three-component alkene oxyalkynylation using H2O or alcohol as oxygenation agent. The reversed regioselectivity should be dictated by an alkene radical cation intermediate.
Y. Li, R. Lu, S. Sun, L. Liu, Org. Lett., 2018, 20, 6836-6839.
The use of N-oxides in butanol as solvent enables a site-selective oxidation of vicinal bis(boronates) with good efficiency and selectivity across a range of substrates to provide 2-hydro-1-boronic esters, which are shown to be versatile intermediates in the synthesis of chiral building blocks.
L. Yan, J. P. Morken, Org. Lett., 2019, 21, 3760-3763.
An NH4I-promoted and H2O-controlled intermolecular difunctionalization of alkenes provides bis-methylsulfanes and β-hydroxysulfides via methylthiyl radical addition to the double bond to give a carbon-centered radical, which immediately cyclizes to a thiiranium ion, followed by combination with H2O to afford β-hydroxysulfides. In the absence of water, 1,2-disulfenylation takes place.
R. He, X. Chen, Y. Li, Q. Liu, C. Liao, L. Chen, Y. Huang, J. Org. Chem., 2019, 84, 8750-8758.
The cyclopropenone catalyzed nucleophilic substitution of alcohols by methanesulfonate ion with inversion of configuration provides an alternative to the Mitsunobu reaction. The new reaction avoids the use of azodicarboxylates and generation of hydrazine and phosphine oxide byproducts and is compatible with a range of functionality.
E. D. Nacsa, T. H. Lambert, Org. Lett., 2013, 15, 38-41.
By careful selection of appropriate enzymes (alcohol dehydrogenases [ADH] and cofactor recycling enzymes), cofactor recycling of NADH can be performed in the presence of NADP+ recycling to achieve overall (R)- or (S)-selective deracemisations of sec-alcohols or stereoinversion representing a possible concept for a “green” equivalent to the chemical-intensive Mitsunobu inversion.
C. V. Voss, C. C. Gruber, K. Faber, T. Knaus, P. Macheroux, W. Kroutil, J. Am. Chem. Soc., 2008, 130, 13969-13972.
A highly efficient dynamic kinetic resolution (DKR) of secondary alcohols at room temperature was developed. In situ racemization of substrates using a Ru catalyst and lipase-catalyzed acylation provides enantiopure products in high yields in very short reaction times. The use of isopropenyl acetate as the acyl donor makes the purification of the products very easy.
B. Martin-Matute, M. Edin, Krisztian Bogar, J.-E. Baeckvall, Angew. Chem. Int. Ed., 2004, 43, 6535-6539.
Well-defined 16-electron ruthenium complexes bearing an N-heterocyclic carbene ligand are active catalysts in the racemization of chiral alcohols. Mechanistic considerations are presented.
J. Bosson, S. P. Nolan, J. Org. Chem., 2010, 75, 2039-2043.