Synthesis of β-methoxyacrylate natural products based on box-Pd(II)-catalyzed intermolecular methoxycarbonylation of alkynoles

A Novel Trisubstituted Tetrahydropyran as a Possible Pheromone Component for the South American Cerambycid Beetle Macropophora accentifer

A novel trisubstituted tetrahydropyran was isolated and identified from the sex-specific volatiles produced by males of the cerambycid beetle Macropophora accentifer (Olivier), a serious pest of citrus and other fruit crops in South America. The compound was the major component in the headspace volatiles, and it was synthesized in racemic form. However, in field trials, the racemate was only weakly attractive to beetles of both sexes, suggesting that attraction might be inhibited by the presence of the "unnatural" enantiomer in the racemate. Alternatively, the male-produced volatiles contained a number of minor and trace components, including a compound tentatively identified as a homolog of the major component, as well as a number of unsaturated 8-carbon alcohols and aldehydes. Further work is required to conclusively identify and synthesize these minor components, to determine whether one or more of them are crucial components of the active pheromone blend for this species.

Photoredox Propargylation of Aldehydes Catalytic in Titanium

A practical and effective photoredox propargylation of aldehydes promoted by 10 mol % of [Cp₂TiCl₂] is presented. No stoichiometric metals or scavengers are used for the process. A catalytic amount of the cheap and simply prepared organic dye 3DPAFIPN is used as the reductant for titanium. The reaction displayed a broad scope, and no traces of allenyl isomers were detected for simple propargyl bromide, whereas mixtures of propargyl and allenyl isomers were observed for substituted propargyl bromides.

Synthesis and Structural Analysis of Palladium(II) Complexes Containing Neutral or Anionic C 2-Symmetric Bis(oxazoline) Ligands: Effects of Substituents in the 5-Position

A series of neutral and cationic palladium(II) complexes containing C ₂-symmetric bis(oxazoline) (BOX) ligands, (BOX)PdCl₂ (2a-d), (BOX)Pd(Me)Cl (3a-d), and [(BOX)PdMe(2,6-Me₂C₅H₃N)]⁺PF₆ ^- (4a-d) [BOX: 2,2'-(2-propylidene)bis{(4R)-4-phenyl-5,5-dimethyl-2-oxazoline}, 2,2'-methylenebis{(4R)-4-phenyl-5,5-dimethyl-2-oxazoline}, 2,2'-methylenebis{(4R)-4,5,5-triphenyl-2-oxazoline}, and 2,2'-methylenebis{(4R,5S)-4,5-diphenyl-2-oxazoline}], were prepared, and their structures were determined by X-ray crystallography. It was found that substituents at the 5-position (Ph, Me) in addition to substituents on the bridgehead carbon directly affect the structure around palladium, especially the BOX bite angle and the dihedral angles between the phenyl rings at the 4-position and the N₂Pd plane. Treatment of the bridged methylene proton in the BOX ligand (1b-d) with KH afforded the anionic BOX ligand; also, the neutral Pd complexes, (BOX)PdMe(2,6-Me₂C₅H₃N) (5b-d), could thus be prepared by reaction with Pd(Me)Cl(cod) (cod = 1,5-cyclooctadiene); 5b-d showed strong coordination to Pd, as demonstrated by X-ray crystallographic analysis.

Pd(ii)-catalyzed ligand controlled synthesis of pyrazole-4-carboxylates and benzo[b]thiophene-3-carboxylates

A simple change of the ligand and solvent allows controlled, effective switching between cyclization–carbonylation–cyclization-coupling (CCC-coupling) and cyclization–carbonylation reactions.

A cyclization–carbonylation–cyclization coupling reaction of (ortho-alkynyl phenyl) (methoxymethyl) sulfides with the palladium(ii)-bisoxazoline catalyst

A CCC-coupling reaction of (o-alkynylphenyl) (methoxymethyl) sulfides, catalyzed by (box)Pd^II complexes, afforded symmetrical ketones bearing two benzo[b]thiophene groups in good to excellent yields.

Pd(ii)-catalyzed ligand controlled synthesis of methyl 1-benzyl-1H-indole-3-carboxylates and bis(1-benzyl-1H-indol-3-yl)methanones

A simple change of ligand and solvent allows controlled, effective switching between cyclization–carbonylation and cyclization–carbonylation–cyclization-coupling (CCC-coupling) reactions.

Palladium-catalyzed oxidative carbonylation reactions

Palladium-catalyzed coupling reactions have become a powerful tool for advanced organic synthesis. This type of reaction is of significant value for the preparation of pharmaceuticals, agrochemicals, as well as advanced materials. Both, academic as well as industrial laboratories continuously investigate new applications of the different methodologies. Clearly, this area constitutes one of the major topics in homogeneous catalysis and organic synthesis. Among the different palladium-catalyzed coupling reactions, several carbonylations have been developed and widely used in organic syntheses and are even applied in the pharmaceutical industry on ton-scale. Furthermore, methodologies such as the carbonylative Suzuki and Sonogashira reactions allow for the preparation of interesting building blocks, which can be easily refined further on. Although carbonylative coupling reactions of aryl halides have been well established, palladium-catalyzed oxidative carbonylation reactions are also interesting. Compared with the reactions of aryl halides, oxidative carbonylation reactions offer an interesting pathway. The oxidative addition step could be potentially avoided in oxidative reactions, but only few reviews exist in this area. In this Minireview, we summarize the recent development in the oxidative carbonylation reactions.