Tetrahedron 65 (2009) 6771–6803 Contents lists available at ScienceDirect Tetrahedron journal homepage: www.elsevier.com/locate/tet Tetrahedron report number 880 Catalytic, asymmetric reactions of ketenes and ketene enolates Daniel H. Paull a, Anthony Weatherwax b, Thomas Lectka a,* a Department of Chemistry, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA b Department of Chemistry, University of Basel, St. Johanns-Ring 19, Basel, CH-4056, Switzerland article info Article history: Received 20 May 2009 Available online 3 June 2009 Keywords: Ketenes Asymmetric reaction Asymmetric synthesis Alcoholysis Aminolysis b-Lactone b-Lactam a-Halogenation Cycloaddition Contents 1. Introduction ................................................................................................................. .............. 6773 1.1. Ketenes and their properties . .......6773 1.2. Structure and reactivity of ketenes . .......6773 1.3. Methods of ketene generation . .....6773 1.4. Cinchona alkaloids as catalysts . ........6774 2. Asymmetric alcoholysis and aminolysis . .......... 6775 2.1. Ketene alcoholysis . .........6775 2.2. Ketene aminolysis . ........6776 3. Asymmetric b-lactone synthesis . 6777 3.1. Cinchona alkaloid catalyst systems . .......6777 3.2. Bifunctional systems . ........6778 3.3. Lewis acid based catalyst systems . ......6779 3.4. Trisubstituted b-lactones ............................................................................................................6781 3.5. Asymmetric ketene dimerization . 6781 3.5.1. Dimerization of preformed ketenes . 6781 3.5.2. Dimerization of in situ generated ketenes . 6782 4. Asymmetric b-lactam synthesis . 6783 4.1. Organocatalytic methodology . 6783 4.2. Bifunctional catalytic methodology . 6784 4.2.1. cis-b-Lactams ...............................................................................................................6784 4.2.2. Mechanistic inquiry . 6785 4.2.3. a-Phenoxy-b-aryl-b-lactams . 6786 * Corresponding author. E-mail address: [email protected] (T. Lectka). 0040-4020/$ – see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.tet.2009.05.079 6772 D.H. Paull et al. / Tetrahedron 65 (2009) 6771–6803 4.3. Trisubstituted b-lactams .............................................................................................................6786 4.3.1. Planar-chiral catalysts . 6786 4.3.2. N-Heterocyclic carbene based catalysis . 6787 4.4. Aza-b-lactams.......................................................................................................................6788 4.5. Oxo-b-lactams ......................................................................................................................6788 5. Asymmetric halogenation . 6788 5.1. a-Chlorination of monosubstituted ketenes . 6789 5.2. a-Bromination of monosubstituted ketenes . 6790 5.3. a-Chlorination of disubstituted ketenes . 6792 5.4. a-Fluorination of dually activated ketenes . 6792 6. Asymmetric [4þ2] cycloaddition reactions . 6793 6.1. o-Benzoquinone derivatives . 6793 6.1.1. o-Quinone reactions . 6794 6.1.2. Bifunctional catalytic o-quinone reactions . 6795 6.1.3. o-Quinone imide reactions . 6796 6.1.4. o-Quinone diimide reactions . 6798 6.2. N-Thioacyl imine reactions . 6799 6.3. Formation of d-lactones .............................................................................................................6799 6.3.1. Conjugate addition/cyclization . ..