The Allenic Pauson−Khand Reaction in Synthesis

Abstract

The Pauson−Khand (PK) reaction is a formal [2+2+1] cycloaddition involving an alkene, an alkyne and carbon monoxide. The allene moiety represents a versatile and useful building block in organic synthesis. In place of the usual alkene, allene reagents are fascinating substrates in the Pauson−Khand‐type reaction because of their unique reactivity and the synthetic utility of the final products. However, there are significant problems of selectivity. Several studies, most of them recent, have greatly enhanced the synthetic utility of this reaction by the use of allenes instead of alkenes. This paper presents recent advances in the less exploited allenic and dienic variants of the Pauson−Khand‐type cycloaddition. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

Allenyl‐β‐lactams: versatile scaffolds for the synthesis of heterocycles

“…Several studies have greatly enhaced the synthetic utility of this process through the use of allenes in place of alkenes. [15] The less exploited allenic variant of the PausonKhand type cycloaddition has been explored in 2‐azetidinone‐tethered allenynes 26 . [16] Substitution patterns on allenynes 26 were selected in order to direct the regiochemical outcome of the cycloaddition to the six‐membered central ring formation because the intramolecular variant of the PausonKhand reaction has been largely restricted to the construction of bicyclo[3.3.0]octenones and bicyclo[4.3.0]nonenones.…”

Rhodium-Catalyzed Carbonylative Synthesis of Heterocycles

“…1-Phenylsulfonylallenes with a hexynyl appendage were treated with catalytic [48]. As there are many research items and reviews published on the Pauson-Khand-type reaction, we do not discuss it extensively here [49][50][51][52][53].…”

Rh(I)-catalyzed Pauson-Khand-type Cycloaddition Reaction of Ene-vinylidenecyclopropanes with Carbon Monoxide (CO)

“…Besides the use of alkyne and alkene as starting materials, allene derivatives including allenynes have also been employed for the Pauson-Khand reaction. 2 In 1994, Narasaka and coworkers reported the first intramolecular version of the Pauson-Khand reaction by using allenynes as substrates in the presence of an iron complex. 3 Later, Brummond's group extensively studied the allene-based Pauson-Khand reaction by using transition metals, molybdenum or rhodium, as the catalysts for highly efficient control of regioselectivity of this cycloaddition reaction.…”