Reactivity of α-Nitro Ketones toward Organometallic Reagents: Straightforward Synthesis of Tertiary β-Nitroalkanols

Article abstract of DOI:10.1021/jo00064a025

Tertiary β-nitro alcohols can be efficiently obtained from the reaction of α-nitro ketones with 2 equiv of an organomagnesium or organolithium reagent.Unexpectedly, Grignard reagents do not deprotonate the α acidic proton of 2 but instead strongly coordinate with the carbonyl and the nitro oxygens.A second equivalent of reagent is thus necessary to carry out the addition.Magnesium reagents fail to react with open-chain α-nitro ketones because a rapid deprotonation occurs, and Grignard reagents are unable to attack monoanion 1.Organolithiums are stronger nucleophiles than organomagnesium reagents and can attack deprotonated substrates.The diastereoselectivity of the reaction depends on the reagent used.Grignard reagents produced almost exclusively trans nitroalkanols with 2, whereas organolithiums show little or no selectivity with the same substrate.Conversely, lithium reagents show excellent stereoselectivity with open-chain substrates and affords the anti diastereomer.