CHAPTER FIVE Organometallic Intermediates of Gold Catalysis Tobias Lauterbach a , Abdullah Mohamed Asiri b , A. Stephen K. Hashmi a,c, * a Organisch-Chemisches Institut, Universita ¨t Heidelberg, Heidelberg, Germany b Center of Excellence for Advanced Materials Research (CEAMR), King Abdulaziz University, Jeddah, Saudi Arabia c Chemistry Department, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia *Corresponding author: e-mail address: hashmi@hashmi.de Contents 1. Introduction 261 2. Organogold Intermediates 262 2.1 π-Complexes 262 2.2 Vinylic organogold complexes 270 2.3 Alkylgold complexes 277 2.4 Gold hydrides 279 2.5 Gem-diaurated complexes and gold acetylides 280 2.6 Gold carbenoids 285 2.7 Gold(III) intermediates 288 3. Conclusions 289 References 290 1. INTRODUCTION The most common reaction pathway for gold-catalyzed reactions is initiated by a π-activation of an alkyne followed by nucleophilic addition to the triple bond. Rearrangements and/or subsequent protodeauration then lead to product formation and regenerate the active gold species. Despite this rather simple reactivity pattern, the isolation and identification of reactive intermediates for many reactions presents a significant challenge. During the last decade, many efforts have been made to deal with this “identity crisis” of mechanistic studies. 1,2 In this review, the synthetic access Advances in Organometallic Chemistry, Volume 62 # 2014 Elsevier Inc. ISSN 0065-3055 All rights reserved. http://dx.doi.org/10.1016/B978-0-12-800976-5.00005-9 261