Palladium-Catalyzed Cascade Oligocyclizations Involving Competing Elementary Steps Such as Thermal [1,5]-Acyl Shifts
| Autor: | Stefan Schweizer, Claudia Thies, Armin de Meijere, Frank E. Meyer, Philip J. Parsons, Wajdi M. Tokan |
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| Rok vydání: | 2009 |
| Předmět: |
Cyclohexane
010405 organic chemistry Chemistry Stereochemistry Organic Chemistry chemistry.chemical_element 010402 general chemistry 01 natural sciences Biochemistry Medicinal chemistry Catalysis 0104 chemical sciences 3. Good health Inorganic Chemistry chemistry.chemical_compound Acetylene Cascade Drug Discovery Benzene derivatives Moiety Physical and Theoretical Chemistry Fulvene Palladium |
| Zdroj: | Helvetica Chimica Acta. 92:1729-1740 |
| ISSN: | 1522-2675 0018-019X |
| DOI: | 10.1002/hlca.200900070 |
| Popis: | Palladium(Pd)-catalyzed oligocyclizations of 2-bromotetradec-1-ene-7,13-diynes with an unsubstituted terminal acetylene moiety like 3 and 5 and 15-bromohexadec-15-ene-3,9-diyn-2-ones like 4 and 6 afforded fulvene derivatives 20 and 21 (Scheme 7) and bis(cyclohexane)-annulated methylenecyclopentene systems 16 and 18 (Schemes 5 and 6), respectively. These transformations constitute cascades of cyclizing carbopalladation steps with ensuing [1,5]-sigmatropic H-atom and acyl shifts, respectively (Scheme 8). In contrast, analogous substrates with one three-atom and one four-atom tether between the unsaturated C,C-bonds, such as 1 and 2, behave differently in that the Pd-substituted hexa-1,3,5-triene intermediates 12 undergo a 6p-electrocyclization instead of a 5-exo-trig carbopalladation followed by s-hydride elimination to furnish tricyclic bis-annulated benzene derivatives 13 and 14 (Scheme 4). |
| Databáze: | OpenAIRE |
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