Intermolecular and Intramolecular Pauson–Khand Reactions of Functionalized Allenes

Abstract

Pauson-Khand reactions of functionalized allenes with different alkynes give cyclopentenones with generally high regio-and stereoselectivities. The allenes react through their external double bonds, giving cyclopentenones with exocyclic double bond at their β positions and predominantly with E stereochemistry. Some intramolecular reactions with al-

Synthesis of Benzazepines by Gold‐Catalysed Reactions of N‐Allenylamides

“…Compound 1a 11 was selected as a model compound and used in reactions performed under different conditions, as summarized in Table 1. The cycloisomerization reactions of allenynes previously described in the literature were postulated to occur by the coordination of the gold atom to the triple bond followed by nucleophilic attack of the internal allene bond to give a cationic species that undergoes a 1,5‐hydrogen shift.…”

Allenamides: A Powerful and Versatile Building Block in Organic Synthesis

“…These reactions were both regio- and stereoselective with several alkynes 453 to give functionalized cyclopentenones 454 bearing an exo -cyclic E -enamide. Subsequently, Pérez-Castells 121 unveiled a Mo(MeCN) 3 (CO) 3 intramolecular Pauson-Khand type reaction of allenamide 455 , leading to tricycle 456 in 43% yield, although the original Co-conditions were not effective (Scheme 120). In it noteworthy that Oh 122 had earlier also demonstrated a molybdenumcatalyzed [2 + 2 + 1] cycloaddition of allenamide 457 to produce compound 458 (Scheme 121).…”

Synthesis and Biological Activity of Novel 1‐Substituted Phenyl‐4‐[N‐[(2′‐morpholinothoxy)phenyl]aminomethyl]‐1H‐1,2,3‐Triazoles

“…According to the literature (17,18), the synthesis of intermediates 4a–c gave consistently poor yields. It was difficult to separate the by‐products in the reaction mixture; 3‐h prolonged reaction in a water bath supersonic device did not help improving the reaction.…”

“…This compound was successfully obtained via reflux in the presence of zinc power in the acetic acid with ethanol and water (V:V, 3:2) as solvents. According to the literature (17,18), the synthesis of intermediates 4a-c gave consistently poor yields. It was difficult to separate the by-products in the reaction mixture; 3-h prolonged reaction in a water bath supersonic device did not help improving the reaction.…”