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Enantioselective ketone reductions convert prochiral ketones into chiral, non-racemic alcohols and are used heavily for the synthesis of stereodefined alcohols. [ 1 ] Carbonyl reduction, the net addition of H 2 across a carbon-oxygen double bond, is an important way to prepare alcohols.
The Corey–Itsuno reduction, also known as the Corey–Bakshi–Shibata (CBS) reduction, is a chemical reaction in which a prochiral ketone is enantioselectively reduced to produce the corresponding chiral, non-racemic alcohol.
Aldehydes and ketones can be reduced respectively to primary and secondary alcohols. In deoxygenation, the alcohol group can be further reduced and removed altogether by replacement with H. Two broad strategies exist for carbonyl reduction. One method, which is favored in industry, uses hydrogen as the reductant.
Oppenauer oxidation, named after Rupert Viktor Oppenauer , [1] is a gentle method for selectively oxidizing secondary alcohols to ketones. Oppenauer oxidation reaction scheme. The reaction is the opposite Meerwein–Ponndorf–Verley reduction. [2] The alcohol is oxidized with aluminium isopropoxide in excess acetone.
The aluminium based Meerwein–Ponndorf–Verley reduction can be performed on prochiral ketones leading to chiral alcohols. The three main ways to achieve the asymmetric reduction is by use of a chiral alcohol hydride source, use of an intramolecular MPV reduction, or use of a chiral ligand on the aluminium alkoxide.
Dimethyl sulfide (Me 2 S) is treated with N-chlorosuccinimide (NCS), resulting in formation of an "active DMSO" species that is used for the activation of the alcohol. Addition of triethylamine to the activated alcohol leads to its oxidation to aldehyde or ketone and generation of dimethyl sulfide. In variance with other alcohol oxidation using ...
The Luche reduction can be conducted chemoselectively toward ketone in the presence of aldehydes or towards α,β-unsaturated ketones in the presence of a non-conjugated ketone. [5] An enone forms an allylic alcohol in a 1,2-addition, and the competing conjugate 1,4-addition is suppressed.
They hypothesized that the secondary alcohol underwent an S N 1 reaction, forming a chloride. Then, an excess amount of zinc reduced the chloride. Importantly, the reaction effectively reduced the two ketones, alcohol, and the methoxycarbonyl group while avoiding any by-products, giving the product in high yield (61%).