Palladium‐Catalyzed Reactions of Propargylic Compounds in Organic Synthesis

Abstract

Palladium was used in organic synthesis lyzed reactions can be classified into sevfor long time only as a heterogeneous eral groups based on their substrates: catalyst for hydrogenating unsaturated organic halides, allylic compounds, concompounds. But in recent years palladi-jugated dienes, alkenes, and alkynes. um compounds have found broad appli-Propargylic compounds undergo a varication as homogeneous catalysts. In the ety of palladium-catalyzed transformalast decade, homogeneous catalysis rely-tions and make up one important class ing on transition metal complexes has of these reactions. It is well known that led to innovations in organic synthesis. copper and silver salts promote or cataComplexes of various transition metals lyze several reactions of propargylic are now used for organic synthesis, and compounds. However, palladium comeach metal has its own characteristic fea-pounds, particularly Pdo complexes, tures. Palladium complexes are the most show catalytic activities entirely differversatile and used extensively in organic ent from those of silver and copper salts. synthesis, particularly for carbon-carAdvances in the research on the palladibon bond formation. Palladium-cata-um-catalyzed reactions of propargylic compounds in the last decade have made the scope of the reactions clear. The ready availability of numerous propargylic alcohols and their esters by the reaction of terminal alkynes with carbonyl compounds clearly enhances the synthetic utility of their reactions. Palladium complexes, in particular palladium phosphane complexes, are soluble in organic solvents and behave as active catalysts under homogeneous conditions.

ESI-FTICR-MS studies on gas phase fragmentation reactions of ArPd(PPh3)2I complexes

“…It is interesting that the ratio of intensities of product ions [PPh 4 ] ϩ and [PPh 3 Ar] ϩ dramatically changes when the functional groups of aromatic halides are changed from electron-donating groups to electron-withdrawing groups ( Table). It seems that the phenyl migration trend is enhanced by the presence of electron-withdrawing substituents such as the nitro group of ion 8, and inhibited by the presence of electron-donating substitu- ents of aromatic halides.…”

“…O rganopalladium complexes [ArPd(R 3 P) 2 X] (X ϭ halogen) play important roles as key intermediates in numerous Pd-catalyzed reactions of aryl halides, such as the Heck arylation of olefins, the Kharasch-Fields, Stille, Suzuki, and Sonogashira coupling reactions, and many nucleophilic displacement and carbonylation reactions [1][2][3][4][5][6]. These complexes provide an attractive point into various Pd-catalyzed cross-couplings, due to both enhanced catalytic activity relative to zerovalent PdL n complexes and ease of handling.…”

Polycondensation behavior between propargyl carbonates having a bulky ester group and bisphenols in the presence of Pd(0) catalyst: synthesis of exomethylene-containing polyethers

“…Polycondensation with propargyl carbonates H Nishino et al Scheme 5 (2). 15 Therefore, the sharp decrease in the M n value would be caused by reaction between the resulting 3b and the methanol liberated from 1a.…”

“…[1][2][3][4][5][6][7][8][9][10][11][12][13] In these reactions, two consecutive nucleophilic attacks occur. A nucleophile attacks at the central carbon of the Z 3 -allenyl/propargyl intermediate generated by reaction of a propargylic carbonate with Pd(0) to yield a p-allylpalladium intermediate, which is successively attacked by a second nucleophile.…”

Stereochemistry of the Asymmetric Carbopalladation of Allenes Followed by Nucleophilic Substitution Reactions with Carbo- and Aminonucleophiles

“…8) Currently, the use of the allene functionality in transition metal-catalyzed reactions has become of great importance from the synthetic and theoretical points of view with regard to the chemical characteristics associated with the axial chirality. [9][10][11][12] Therefore, an allene with the axial chirality might be a synthetically useful chiral director for the elaboration of chiral complex organic molecules in asymmetric synthesis with metal catalysts. For the approach to chiral allenes, however, few synthetically useful methodology has been devised so far by asymmetric synthesis, especially with catalytic versions, [13][14][15][16][17] despite the efforts to access chiral allenes that were made by many investigators.…”