Straightforward Synthesis of Allylated Keto Esters: The Palladium-Catalysed Haloketone Alkoxycarbonylation/ Allylation Domino Reaction

Boron-catalyzed dehydrative allylation of 1,3-diketones and β-ketone esters with 1,3-diarylallyl alcohols in water

A metal-free catalytic allylation with atom economy and green environment friendly was developed. Allylic alcohols could be directly dehydrated in water by B(C6F5)3, without using any base additives. The reaction can afford the corresponding monoallylated product in moderate to high yield and has been performed on a gram-scale, and a quaternary carbon center can be constructed for the active methine compounds of 1,3-diketones or β-ketone esters in this process. The product can be further converted, such as the synthesis of tetra-substituted pyrazole compounds, or 1,4-dienes and functionalized dihydropyrans.

Pd-Catalyzed tandem C–C/C–O/C–H single bond cleavage of 3-allyloxybenzocyclobutenols

A Pd-catalyzed skeletal rearrangement of 3-allyloxybenzocyclobutenols was achieved, which involved tandem C–C/C–O bond cleavage and C–H allylic substitution.

Switchable selectivity in Pd-catalyzed [3 + 2] annulations of γ-oxy-2-cycloalkenones with 3-oxoglutarates: C-C/C-C vs C-C/O-C bond formation

Two complementary [3 + 2] annulation protocols between 3-oxoglutarates and cyclic γ-oxy-2-cycloalkenones, simply differing on the reaction temperature, are disclosed. These domino transformations allow C-C/O-C or C-C/C-C [3 + 2] annulations at will, via an intermolecular Pd-catalyzed C-allylation/intramolecular O- or C-1,4-addition sequence, respectively. In particular, exploiting the reversibility of the O-1,4-addition step, in combination with the irreversible C-1,4-addition/decarboxylation path, the intramolecular conjugate addition step could be diverted from the kinetic (O-alkylation) to the thermodynamic path (C-alkylation) thanks to a simple temperature increase. Crucial for the success of this bis-nucleophile/bis-electrophile [3 + 2] annulation is its well-defined step chronology in combination with the total chemoselectivity of the former step. This [3 + 2] C-C/O-C bond forming annulation protocol could be also extended to 1,3,5-triketones as well as 1,3-bis-sulfonylpropan-2-one bis-nucleophiles.

Featuring Xantphos

This review highlights the use of the bisphosphine ligand group in homogeneous catalysis.

Highly selective palladium-benzothiazole carbene-catalyzed allylation of active methylene compounds under neutral conditions

The Pd–benzothiazol-2-ylidene complex I was found to be a chemoselective catalyst for the Tsuji–Trost allylation of active methylene compounds carried out under neutral conditions and using carbonates as allylating agents. The proposed protocol consists in a simplified procedure adopting an in situ prepared catalyst from Pd₂dba₃ and 3-methylbenzothiazolium salt V as precursors. A comparison of the performance of benzothiazole carbene with phosphanes and an analogous imidazolium carbene ligand is also proposed.

Synthesis of aromatic β-keto esters via a carbonylative Suzuki–Miyaura coupling reaction of α-iodo esters with arylboronic acids

Aromatic β-keto esters were synthesized via a carbonylative cross-coupling reaction of alkyl iodides and arylboronic acids in the presence of a catalytic amount of Pd catalyst.

Condition-determined multicomponent reactions of 1,3-dicarbonyl compounds and formaldehyde

By means of changing the reaction parameters, different products could be generated selectively starting from the same combination of substrates involving 1,3-dicarbonyl compounds and formaldehyde. This strategy enabled us to access diverse molecules without changing both starting material and reactor, maximizing thus the multifunctionality of the synthetic system. For example, starting from a 1,3-dicarbonyl compound, formaldehyde and 1,1-diphenylethylene, two kinds of products could be selectively formed including (i) a densely substituted dihydropyran and (ii) a C2-cinnamyl substituted 1,3-dicarbonyl compound. A one-pot three-component reaction of phenacylpyridinium salt, 1,3-dicarbonyl compound, and formaldehyde was also investigated, which produced either 2,4-diacyl-2,3-dihydrofuran or 2,4-diacyl-2-hydroxylmethyl-2,3-dihydrofuran in good to excellent yield.