Categories: O-H Bond Formation >
Reduction of carboxyl compounds to alcohols
Pincer ruthenium complexes bearing a monodentate N-heterocyclic carbene ligand have been used as powerful hydrogenation catalysts. With an atmospheric pressure of hydrogen gas, aromatic, heteroaromatic, and aliphatic esters as well as lactones were converted into the corresponding alcohols.
O. Ogata, Y. Nakayama, H. Nara, M. Fujiwhara, Y. Kayaki, J. Zhu, Org. Lett., 2016, 18, 3894-3897.
A catalytic system of cobalt(II) chloride and diisopropylamine in combination with NaBH4 showed excellent activity in the chemoselective reduction of various carboxylic esters to their corresponding alcohols in very good yields under mild conditions. Unsaturated carboxylic esters give saturated alcohols in high yields.
A. R. Jagdale, A. S. Paraskar, A. Sudalai, Synthesis, 2009, 660-664.
A well-defined manganese(I) complex with a commercially available bisphosphine ligand catalyzes selective and efficient hydrosilylations of a broad range of esters to alcohols at 100 °C under solvent-free conditions.
R. R. Behera, R. Ghosh, S. Panda, S. Khamari, B. Bagh, Org. Lett., 2020, 22, 3642-3648.
A manganese-catalyzed chemoselective hydroboration of carboxylic acids to the corresponding alcohols offers a high turnover number and turnover frequency at 25°C. This method tolerates electronically and sterically differentiated substrates with high chemoselectivity. Importantly, aliphatic long-chain fatty acids, including biomass-derived compounds, can efficiently be reduced.
M. K. Barman, K. Das, B. Maji, J. Org. Chem., 2019, 84, 1570-1579.
Odorless Dod-S-Me and MMS are developed as efficient borane carriers. The yields of hydroborations and reductions with the borane complex of Dod-S-Me are very high. The recovery of Dod-S-Me after the reaction is quantitative.
P. K. Patra, K. Nishide, K. Fuji, M. Node, Synthesis, 2004, 1003-1006.
The use of D2O and SmI2 as a mild single-electron donor enables a general single-electron transfer reductive deuteration of readily commercially available aromatic esters for the synthesis of α,α-dideuterio benzyl alcohols. This operationally convenient method features high deuterium incorporations and very good functional group tolerance.
S. Luo, C. Weng, Y. Ding, C. Ling, M. Szostak, X. Ma, J. An, Synlett, 2021, 32, 51-56.
The use of pentafluorophenyl esters as ketyl radical precursors, SmI2 as a mild reducing agent, and D2O as the deuterium source enables a highly chemoselective synthesis of α,α-dideuterio alcohols with exquisite incorporation of deuterium. This system tolerates a variety of functional groups.
H. Li, Y. Hou, C. Liu, Z. Lai, L. Ning, R. Szostak, M. Szostak, J. An, Org. Lett., 2020, 22, 1249-1253.
A practical and scalable single electron transfer reduction enables the reduction and reductive deuteration of tertiary amides in the presence of sodium dispersions. The chemoselectivity of this method highly depends on the nature of the proton donor. Whereas the combination of Na/EtOH affords alcohol products, the use of Na/NaOH/H2O leads to the formation of amines.
B. Zhang, H. Li, Y. Ding, Y. Yan, J. An, J. Org. Chem., 2018, 83, 6006-6014.
A highly chemoselective direct reduction of primary, secondary, and tertiary amides to alcohols in high yields in presence of SmI2/amine/H2O proceeds via C-N bond cleavage in a carbinolamine intermediate and shows excellent functional group tolerance. The expected C-O cleavage products are not formed under the reaction conditions. Notably, the method provides direct access to acyl-type radicals from unactivated amides under mild conditions.
M. Szostak, M. Spain, A. J. Eberhard, D. J. Procter, J. Am. Chem. Soc., 2014, 136, 2268-2271.
A simple and practical protocol for the reduction of carboxylic acids via in situ formation of hydroxybenzotriazole esters followed by reaction with sodium borohydride gives the corresponding alcohols. The reaction proceeds with excellent yields in the presence of water.
J. A. Morales-Serna, E. García-Rios, J. Bernal, E. Paleo, R. Gaviño, J. Cárdenas, Synthesis, 2011, 1375-1382.
The preparation of alkenyl halides of any length from inexpensive starting reagents is reported. Standard organic transformations were used to prepare straight-chain α-olefin halides in excellent overall yields with no detectable olefin isomerization and full recovery of any unreacted starting material.
T. W. Baughman, J. C. Sworen, K. B. Wagener, Tetrahedron, 2004, 60, 10943-10948.
The use of diethylaluminum benzenethiolate enables an efficient discrimination between aldehydes and other carbonyl functions and allows a chemoselective in situ reduction of ketones and methyl esters in the presence of aldehydes without using traditional protecting group methodologies.
G. Bastug, S. Dierick, F. Lebreux, I. E. Markó, Org. Lett., 2012, 14, 1306-1309.