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Henry C, Bolien D, Ibanescu B, Bloodworth S, Harrowven DC, Zhang X, Craven A, Sneddon HF, Whitby RJ. Generation and Trapping of Ketenes in Flow. European J Org Chem 2015; 2015:1491-1499. [PMID: 26097406 PMCID: PMC4464552 DOI: 10.1002/ejoc.201403603] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Indexed: 01/21/2023]
Abstract
Ketenes were generated by the thermolysis of alkoxyalkynes under flow conditions, and then trapped with amines and alcohols to cleanly give amides and esters. For a 10 min reaction time, temperatures of 180, 160, and 140 °C were required for >95 % conversion of EtO, iPrO, and tBuO alkoxyalkynes, respectively. Variation of the temperature and flow rate with inline monitoring of the output by IR spectroscopy allowed the kinetic parameters for the conversion of 1-ethoxy-1-octyne to be easily estimated (Ea = 105.4 kJ/mol). Trapping of the in-situ-generated ketenes by alcohols to give esters required the addition of a tertiary amine catalyst to prevent competitive [2+2] addition of the ketene to the alkoxyalkyne precursor.
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Affiliation(s)
- Cyril Henry
- Chemistry, University of SouthamptonSouthampton, HANTS, SO17 1BJ, UK
| | - David Bolien
- Chemistry, University of SouthamptonSouthampton, HANTS, SO17 1BJ, UK
| | - Bogdan Ibanescu
- Chemistry, University of SouthamptonSouthampton, HANTS, SO17 1BJ, UK
| | - Sally Bloodworth
- Chemistry, University of SouthamptonSouthampton, HANTS, SO17 1BJ, UK
| | - David C Harrowven
- Chemistry, University of SouthamptonSouthampton, HANTS, SO17 1BJ, UK
| | - Xunli Zhang
- Bioengineering Group, Faculty of Engineering and the Environment, University of SouthamptonSouthampton, HANTS, SO17 1BJ, UK
| | - Andy Craven
- GlaxoSmithKline R&D Ltd., Medicines Research CentreGunnels Wood Road, Stevenage, HERTS, SG1 2NY, UK
| | - Helen F Sneddon
- GlaxoSmithKline R&D Ltd., Medicines Research CentreGunnels Wood Road, Stevenage, HERTS, SG1 2NY, UK
| | - Richard J Whitby
- Chemistry, University of SouthamptonSouthampton, HANTS, SO17 1BJ, UK
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