1,3-Difunctionalization of β-Alkyl Nitroalkenes via Combination of Lewis Base Catalysis and Radical Oxidation

Upon treatment with a Lewis base catalyst, β-alkyl-substituted nitroalkenes could be readily converted into allylic nitro compounds. Examples of either C-1 or C-3 functionalization methods have been reported through nitro-elimination, giving alkene products. In this work, successful 1,3-difunctionalization was achieved through a synergetic Lewis base catalysis and TBHP radical oxidation, giving vinylic alkoxyamines in good to excellent yields. This work further extended the general synthetic application of β-alkyl nitroalkenes.

Synthetic Approach to the Preparation of (2-Acetoxy)allyl Nitro Compounds

A synthetic approach to a new class of allyl nitro derivatives is reported. (2-Acetoxy)allyl nitro compounds have been prepared for the first time in a four-step procedure by a preliminary reaction of nitroalkanes with 2-(phenylselenyl)acetaldehyde. After the acetylation of the obtained nitro alcohols, the unsaturation is installed by an oxidation reaction involving the phenylselenyl group followed by a thermal elimination. The oxidation process is accomplished under flow conditions ensuring a notable lowering of overoxidation by products observed in batch.

Allylic C-S Bond Construction through Metal-Free Direct Nitroalkene Sulfonation

A metal-free, open-flask protocol was developed for the preparation of allylic sulfones through direct condensation of sodium arylsulfinates and β,β-disubstituted nitroalkenes. The key step of this process was the Lewis base-promoted equilibrium between nitroalkenes and allylic nitro compounds. Through this process, the readily available conjugated nitroalkenes can be easily converted into allylic nitro compounds, which contain more reactive C═C bonds toward the sulfonyl radical addition. As a result, allylic sulfones were prepared in excellent yields with a broad substrate scope under mild conditions.

Asymmetric synthesis of substituted NH-piperidines from chiral amines

Previously, we reported an efficient asymmetric synthesis of substituted piperidines through an exocyclic chirality induced nitroalkene/amine/enone (NAE) condensation reaction. An effective protecting group strategy was developed herein to achieve enantiopure piperidines (yields up to 92%) with complete chirality retention (ee > 95%). A simple derivatization of the obtained piperidines gave thiourea catalysts, indicating the strong potential of this method for producing new amine-based dual functional organocatalysts for future development.

Michael addition/pericyclization/rearrangement--a multicomponent strategy for the synthesis of substituted resorcinols

The combination of methyl 3,7-dioxo-2-diazo-4-octenoate from the zinc triflate catalyzed Mukaiyama-Michael reaction of methyl 3-tert-butylsilyloxy-2-diazobutenoate and 4-methoxy-3-buten-2-one with Michael acceptors (methyl vinyl ketone, N-phenylmaleimide, β-nitrovinylarenes) in the presence of a catalytic amount of base provides convenient access to highly substituted resorcinol derivatives. This transformation is achieved in an efficient one-pot multi-component transformation by the sequential addition of the reagents.