The Mechanism of the Pauson-Khand Reaction: Hypothesis, Experimental Facts, and Theoretical Investigations - The Pauson-Khand Reaction - page 22

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The Mechanism of the Pauson-Khand
Reaction: Hypothesis, Experimental
Facts, and Theoretical Investigations

Xacobe C. Cambeiro and Miquel A. Pericas

2.1 Introduction 23

2.2 Stoichiometric Pauson-Khand Reaction 25

2.2.1 The Ligand Substitution Steps 25

2.2.2 Cobaltacycle Formation 29

2.2.3 CO Insertion 31

2.2.4 Reductive Elimination 32

2.3 Catalytic Pauson-Khand Reaction 32

2.4 Theoretical Studies 33

2.4.1 General Approach to the Mechanism 33

2.4.2 Regioselectivity. Early Steps of the Pauson-Khand Reaction 37

2.4.3 Stereoselectivity 41

2.5 Conclusions 46

References 46

2.1 Introduction

The prototypal Pauson-Khand (PK) synthesis of cyclopentenones, first introduced in 1973, 1
combines in a single step an alkyne, an alkene, and carbon monoxide (coming from oc-
tacarbonyl dicobalt) in a regioselective and stereoselective manner (Scheme 2.1). For this