The most useful strategies for the alkylation of allylic systems are related to the Tsuji–Trost reaction or the use of different Lewis acids. Herein we report a photocatalytic approach for the allylation reaction of a variety of nucleophiles, such as heteroarenes, amines and alcohols. This method is compatible with a large variety of pyrroles and indoles, containing different substituents such as electron-withdrawing and electron-donating groups, unprotected nitrogen atoms and bromo derivatives. Moreover, this methodology enables the chromoselective synthesis of Z - or E -allylated compounds. While the use of UV-light irradiation has allowed the synthesis of the previously inaccessible Z -allylated products, E -isomers are prepared simply by changing both the light source to the visible region, and the catalytic system. Based on mechanistic and photochemical proofs, laser flash photolysis studies and DFT calculations, a rational mechanism is presented.

Described herein is a new visible-light photocatalytic strategy for the synthesis of enantioenriched dihydrofurans and cyclopentenes by an intramolecular nitro cyclopropane ring expansion reaction. Mechanistic studies and DFT calculations are used to elucidate the key factors in this new ring expansion reaction, and the need for the nitro group on the cyclopropane.

A metal‐free synthesis of biologically important benzazepines is achieved through a single synthetic operation involving an oxidative C–H bond functionalization and ring expansion with diazomethanes as key reagent. This represents a new, strong methodology for the straightforward construction of the seven‐ring N‐heterocyclic structures under mild conditions using a 2,2,6,6‐tetramethylpiperidine 1‐oxyl (TEMPO) oxoammonium salt as oxidant. Moderate to good yields are achieved from simple, readily available tetrahydroisoquinolines, and this methodology has been further successfully applied for the synthesis of the 3‐benzazepine drug Lorcaserin. A possible mechanistic pathway for the ring expansion step, comprising the extrusion of nitrogen in a concerted asynchronic process, is proposed based on both mechanistic proof and density function theory (DFT) calculations.magnified image

A well-established strategy to synthesize heterogeneous, metal-organic framework (MOF) catalysts that exhibit nanoconfinement effects, and specific pores with highly-localized catalytic sites, is to use organic linkers containing organocatalytic centers. Here, we report that by combining this linker approach with reticular chemistry, and exploiting three-dimensioanl (3D) MOF-structural data from the Cambridge Structural Database, we have designed four heterogeneous MOF-based catalysts for standard organic transformations. These programmable MOFs are isoreticular versions of pcu IRMOF-16, fcu UiO-68 and pillared-pcu SNU-8X, the three most common topologies of MOFs built from the organic linker p,p'-terphenyldicarboxylic acid (tpdc). To synthesize the four squaramide-based MOFs, we designed and synthesized a linker, 4,4'-((3,4dioxocyclobut-1-ene-1,2-diyl)bis(azanedyil))dibenzoic acid (Sq_tpdc), which is identical in directionality and length to tpdc but which contains organocatalytic squaramide centers. Squaramides were chosen because their immobilization into a framework enhances its reactivity and stability while avoiding any self-quenching phenomena. Therefore, the four MOFs share the same organocatalytic squaramide moiety, but confine it within distinct pore environments. We then evaluated these MOFs as heterogeneous H-bonding catalysts in organic transformations: a Friedel-Crafts alkylation and an epoxide ring-opening. Some of them exhibited good performance in both reactions but all showed distinct catalytic profiles that reflect their structural differences.

Tandem and multicomponent one‐pot reactions are highly attractive because they enable synthesis of target molecules in a single reaction vessel. However, they are difficult to control, as they can lead to the formation of many undesired side‐products. Herein we report the use of metal‐organic framework (MOF) pores decorated with organocatalytic squaramide moieties to confine ring‐opening epoxide reactions of diverse substrates. Controlled mono‐addition or tandem reactions inside the pores yield 1,2‐aminoalcohols or 1,2,2′‐aminodialcohols, respectively, in good yields. In addition, this squaramide‐functionalised MOF enables catalysis of higher‐complexity multicomponent reactions such as the catalytic ring‐opening of two different epoxides by a single amine to afford 1,2,2′‐aminodialcohols.