Photoinduced Multicomponent Reactions.

The combination of multicomponent approaches with light-driven processes opens up new scenarios in the area of synthetic organic chemistry, where the need for sustainable, atom- and energy-efficient reactions is increasingly urgent. Photoinduced multicomponent reactions are still in their infancy, but significant developments in this area are expected in the near future.

Three in the spotlight: Photoinduced stereoselective synthesis of (Z)-acyloxyacrylamides through a multicomponent approach.

We report a straightforward approach to synthesize 2-acyloxyacrylamides, which are useful synthons in organic synthesis. This involves a photoactivated multicomponent reaction, performed both in batch and under continuous flow conditions. This process affords the desired compounds in a stereoselective fashion from readily available starting materials in one step, without the aid of metal catalysis. This paper illustrates the preliminary work, the extensive experiments carried out to understand the limitations of the approach, and the optimization of the conditions for the synthesis of these particular captodative olefins.

Exploitation of the Ugi 5-Center-4-Component Reaction (U-5C-4CR) for the Generation of Diverse Libraries of Polycyclic (Spiro)Compounds.

An Ugi multicomponent reaction with chiral cyclic amino acids, benzyl isocyanide and cyclic ketones (or acetone) has been exploited as key step for the generation of peptidomimetics. After a straightforward set of elaborations, the peptidomimetics were converted into polycyclic scaffolds displaying two orthogonally protected secondary amines. Libraries of compounds were obtained decorating the molecules through acylation/reductive amination reactions on these functional groups.

Corrigendum: Exploitation of the Ugi 5-Center-4-Component Reaction (U-5C-4CR) for the Generation of Diverse Libraries of Polycyclic (Spiro)Compounds.

[This corrects the article DOI: 10.3389/fchem.2018.00369.].

Photoinduced Multicomponent Synthesis of α-Silyloxy Acrylamides, an Unexplored Class of Silyl Enol Ethers.

The photoinduced, multicomponent reaction of α-diazoketones, silanols, and isocyanides affords α-silyloxy acrylamides, formally derived from α-keto amides. The presence of a secondary amido group makes classic preparative methods for silyl enol ethers unfeasible in this case, while the mild conditions required by this photochemical approach allow their synthesis in good yields; moreover, the general structure can be easily modified by varying each component of the multicomponent reaction. Fine-tuning of the reaction conditions (i.e., solvents, radiation, additives) can be exploited to obtain complete Z selectivity. The reactivity of this overlooked class of silyl enol ethers has been investigated, and features that could pave the way to new applications have been found.