In Pauson-Khand reaction

Wilkinson s catalyst also allows the intramolecular cycloisomerization of allenynes 243 to interesting cross-conjugated trienes 244 (Scheme 15.76) [146], Similar compounds are observed as side-products in Pauson-Khand reactions of allenynes [147]. 

Amine—bis(amide) ligands, in chromium(III) models, 5, 376 Amine 7V-oxide promoters, in Pauson—Khand reaction with dicobalt octacarbonyl, 11, 337 Amines... 

Cyclobutenes, in Pauson-Khand reaction, 11, 352 Cyclocarbonylation reactions, alkynes, 10, 714 Cyclo-C3 complexes, with molybdenum carbonyls, 5, 440 Cyclo-C4 complexes, in molybdenum carbonyls, 5, 448 Cyclochrome P450cam, aryldiazene reactions, 6, 107 Cyclodextrins... 

Dicobalt octacarbonyl, in Pauson—Khand reaction homogeneous catalysis, 11, 340 metal-coupled promoters, 11, 339 non-oxidative promoter-assisted, 11, 338 oxidative promoter-assisted, 11, 337 physical promoters, 11, 339 solid-supported promoters, 11, 339 Dicobalt triple-decker sandwiches, preparation, 3, 14 (+)-Dictamnol, via [5+2]-cycloadditions, 10, 613-614 Dicyclohexylborane, for alkene hydroboration, 9, 150... 

Oxidative alkoxycarbonylation asymmetric carbonylation, 11, 467 catalyst development, 11, 467 mechanism, 11, 466 Oxidative amination, olefins, 10, 155 Oxidative cleavage, mechanisms, 1, 103 Oxidative promoters, in Pauson-Khand reaction with dicobalt octacarbonyl, 11, 337... 

Pauson-Khand Cycloaddition. Pauson Khand cycloaddition (see Pauson-Khand Reaction) is a cobalt-mediated method to prepare cyclopentenone from the cyclization of an alkyne with an alkene and CO (equation 14). This method is widely used to produce cychc ketones. Originally, stoichiometric amounts of Co2(CO)g were used in these reactions with the cobalt carbonyl being the CO source. However, it was shown that a strict temperature profile and high-purity reagents allowed the use of catalytic amounts of Co2(CO)g for reactions with 1 atm of CO. Currently, there is intense interest in developing catalytic cobalt starting materials for use in Pauson-Khand reactions. 

Cyclopropene can also be used as the aUcene component and affords bicyclo[3.1.0]hexen-2-ones upon reaction with alkyne dicobalt octacarbonyl complexes in the presence of NMO (Scheme 250). Vinyl ethers and vinyl esters serve as ethene equivalents in Pauson-Khand reactions. For example, reaction of vinyl benzoate with complex (169) furnished cyclopentenone (170) (Scheme 251). This reaction was used in a synthesis of (-l-)-taylorine and nortaylorine. Allenes participate in intermolecular Pauson-Khand reactions affording alkylidene-substituted cyclopentenones (Scheme 252). ... 

Schulte, J. H., Gleiter, R., Rominger, F. Regiochemistry of S-Alkyl-Substituted Alkynes in Pauson-Khand Reactions. Is a Correlation with X-ray Data and Charge Distribution Calculations of the Co2(CO)6-Alkyne Complexes Possible Org. Lett. 2002,4, 3301-3304. 

Derdau, V., Laschat, S., Jones, P. G. Evaluation of the regioselectivity in Pauson-Khand reactions of substituted norbornenes and diazabicyclo[2.2.1]heptanes with terminal alkynes. Eur. J. Org. Chem. 2000, 681-689. 

Figure 4.4 Cobalt alkyne complex in the presence of cinchona N-oxide in Pauson-Khand reaction.

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