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Pupo G, Gouverneur V. Hydrogen Bonding Phase-Transfer Catalysis with Alkali Metal Fluorides and Beyond. J Am Chem Soc 2022; 144:5200-5213. [PMID: 35294171 PMCID: PMC9084554 DOI: 10.1021/jacs.2c00190] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Phase-transfer catalysis (PTC) is one of the most powerful catalytic manifolds for asymmetric synthesis. Chiral cationic or anionic PTC strategies have enabled a variety of transformations, yet studies on the use of insoluble inorganic salts as nucleophiles for the synthesis of enantioenriched molecules have remained elusive. A long-standing challenge is the development of methods for asymmetric carbon-fluorine bond formation from readily available and cost-effective alkali metal fluorides. In this Perspective, we describe how H-bond donors can provide a solution through fluoride binding. We use examples, primarily from our own research, to discuss how hydrogen bonding interactions impact fluoride reactivity and the role of H-bond donors as phase-transfer catalysts to bring solid-phase alkali metal fluorides in solution. These studies led to hydrogen bonding phase-transfer catalysis (HB-PTC), a new concept in PTC, originally crafted for alkali metal fluorides but offering opportunities beyond enantioselective fluorination. Looking ahead, the unlimited options that one can consider to diversify the H-bond donor, the inorganic salt, and the electrophile, herald a new era in phase-transfer catalysis. Whether abundant inorganic salts of lattice energy significantly higher than those studied to date could be considered as nucleophiles, e.g., CaF2, remains an open question, with solutions that may be found through synergistic PTC catalysis or beyond PTC.
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Affiliation(s)
- Gabriele Pupo
- Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, U.K
| | - Véronique Gouverneur
- Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, U.K
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Roagna G, Ascough DMH, Ibba F, Vicini AC, Fontana A, Christensen KE, Peschiulli A, Oehlrich D, Misale A, Trabanco AA, Paton RS, Pupo G, Gouverneur V. Hydrogen Bonding Phase-Transfer Catalysis with Ionic Reactants: Enantioselective Synthesis of γ-Fluoroamines. J Am Chem Soc 2020; 142:14045-14051. [PMID: 32608977 PMCID: PMC7441491 DOI: 10.1021/jacs.0c05131] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
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Ammonium
salts are used as phase-transfer catalysts for fluorination
with alkali metal fluorides. We now demonstrate that these organic
salts, specifically azetidinium triflates, are suitable substrates
for enantioselective ring opening with CsF and a chiral bis-urea catalyst. This process, which highlights the ability of hydrogen
bonding phase-transfer catalysts to couple two ionic reactants, affords
enantioenriched γ-fluoroamines in high yields. Mechanistic studies
underline the role of the catalyst for phase-transfer, and computed
transition state structures account for the enantioconvergence observed
for mixtures of achiral azetidinium diastereomers. The N-substituents
in the electrophile influence the reactivity, but the configuration
at nitrogen is unimportant for the enantioselectivity.
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Affiliation(s)
- Giulia Roagna
- University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, Oxford OX1 3TA, U.K
| | - David M H Ascough
- University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, Oxford OX1 3TA, U.K
| | - Francesco Ibba
- University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, Oxford OX1 3TA, U.K
| | - Anna Chiara Vicini
- University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, Oxford OX1 3TA, U.K
| | - Alberto Fontana
- Discovery Chemistry, Janssen Research & Development, Janssen-Cilag S.A., Calle Jarama 75A, 45007 Toledo, Spain
| | - Kirsten E Christensen
- University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, Oxford OX1 3TA, U.K
| | - Aldo Peschiulli
- Discovery Sciences Medicinal Chemistry, Janssen Research & Development, Janssen Pharmaceutica N.V., Turnhoutseweg 30, B-2340 Beerse, Belgium
| | - Daniel Oehlrich
- Discovery Sciences Medicinal Chemistry, Janssen Research & Development, Janssen Pharmaceutica N.V., Turnhoutseweg 30, B-2340 Beerse, Belgium
| | - Antonio Misale
- Discovery Chemistry, Janssen Research & Development, Janssen-Cilag S.A., Calle Jarama 75A, 45007 Toledo, Spain
| | - Andrés A Trabanco
- Discovery Chemistry, Janssen Research & Development, Janssen-Cilag S.A., Calle Jarama 75A, 45007 Toledo, Spain
| | - Robert S Paton
- University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, Oxford OX1 3TA, U.K.,Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Gabriele Pupo
- University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, Oxford OX1 3TA, U.K
| | - Véronique Gouverneur
- University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, Oxford OX1 3TA, U.K
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Seto H, Qian ZH, Yoshioka H, Uchibori Y, Umeno M. Facile Preparation of Tetrabutylphosphonium Fluoride and Its HF Adducts. New Fluoride Anion Sources for Selective Nucleophilic Fluorination. CHEM LETT 1991. [DOI: 10.1246/cl.1991.1185] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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