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Caravez JC, Hu Y, Oftadeh E, Mamo KT, Lipshutz BH. Preparation of a Key Intermediate En Route to the Anti-HIV Drug Lenacapavir. J Org Chem 2024; 89:3995-4000. [PMID: 38447077 PMCID: PMC10949239 DOI: 10.1021/acs.joc.3c02855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 02/12/2024] [Accepted: 02/19/2024] [Indexed: 03/08/2024]
Abstract
A very efficient four-step synthesis of the main fragment of Gilead's anti-HIV drug lenacapavir is described. The route showcases a 1,2-addition to an intermediate aldehyde using an organozinc halide derived from a commercially available difluorobenzyl Grignard reagent. This sets the stage for the oxidation of the resulting secondary alcohol to the desired ketone, which relies solely on catalytic amounts of TEMPO together with NaClO as the terminal oxidant, affording the targeted ketone in 67% overall yield.
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Affiliation(s)
- Juan C. Caravez
- Department of Chemistry &
Biochemistry, University of California, Santa Barbara, CA 93106, United States
| | - Yuting Hu
- Department of Chemistry &
Biochemistry, University of California, Santa Barbara, CA 93106, United States
| | - Erfan Oftadeh
- Department of Chemistry &
Biochemistry, University of California, Santa Barbara, CA 93106, United States
| | - Kirubel T. Mamo
- Department of Chemistry &
Biochemistry, University of California, Santa Barbara, CA 93106, United States
| | - Bruce H. Lipshutz
- Department of Chemistry &
Biochemistry, University of California, Santa Barbara, CA 93106, United States
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Kumar R, Li G, Gallardo VA, Li A, Milton J, Nash JJ, Kenttämaa HI. Measurement of the Proton Affinities of a Series of Mono- and Biradicals of Pyridine. J Am Chem Soc 2020; 142:8679-8687. [PMID: 32315166 DOI: 10.1021/jacs.0c00202] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The proton affinity (PA) of a neutral molecule is defined as the negative of the enthalpy change for the gas-phase reaction between a proton and the neutral molecule to produce the (charged) conjugate acid of the molecule. PA is a fundamental property that is related to the structure of a molecule and affects its reactivity. Very few PA values are available for basic organic monoradicals and none for biradicals. Here, the PA values for several σ-type carbon-centered pyridine-based monoradicals and biradicals have been experimentally determined by monitoring proton transfer from the protonated mono- and biradicals to reference bases with known proton affinities as a function of time in Fourier-transform ion cyclotron resonance (FT-ICR) and linear quadrupole ion trap (LQIT) mass spectrometers. A procedure was developed for both instruments that permits differentiation between exo- and endothermic proton transfer reactions. The PA values of all the (bi)radicals studied were found to be lower than that of pyridine. This is rationalized based on the electron-withdrawing nature of the radical site(s). Thus, the PA values decrease in the order: pyridine > monoradicals > biradicals. The PA values of the monoradicals were also found to increase (making the protonated radicals less acidic) as the distance between the basic nitrogen atom and the radical site increases. Similar behavior was found for the biradicals, with one exception: 3,5-didehydropyridine has a larger PA (215.3 ± 3.3 kcal mol-1) than 3,4-didehydropyridine (PA = 213.4 ± 3.3 kcal mol-1) even though the latter biradical has one radical site farther away from the basic nitrogen atom. Quantum chemical calculations of the PAs of the (bi)radicals are in reasonably good agreement with the experimentally determined values. At the DFT (B3LYP), CCSD(T), and CASPT2 levels of theory, the mean unsigned errors are 2.3, 1.7, and 2.1 kcal mol-1.
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Affiliation(s)
- Rashmi Kumar
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
| | - Guannan Li
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
| | - Vanessa A Gallardo
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
| | - Anyin Li
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
| | - Jacob Milton
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
| | - John J Nash
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
| | - Hilkka I Kenttämaa
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
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Ma X, Jin C, Wang D, Nash JJ, Kenttämaa HI. Relative Reactivities of Three Isomeric Aromatic Biradicals with a 1,4‐Biradical Topology Are Controlled by Polar Effects. Chemistry 2019; 25:6355-6361. [PMID: 30811712 DOI: 10.1002/chem.201806106] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2018] [Revised: 02/24/2019] [Indexed: 01/22/2023]
Affiliation(s)
- Xin Ma
- Department of ChemistryPurdue University 560 Oval Drive West Lafayette Indiana 47907 USA
| | - Chunfen Jin
- Department of ChemistryPurdue University 560 Oval Drive West Lafayette Indiana 47907 USA
| | - Duanda Wang
- Department of ChemistryPurdue University 560 Oval Drive West Lafayette Indiana 47907 USA
| | - John J. Nash
- Department of ChemistryPurdue University 560 Oval Drive West Lafayette Indiana 47907 USA
| | - Hilkka I. Kenttämaa
- Department of ChemistryPurdue University 560 Oval Drive West Lafayette Indiana 47907 USA
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Sheng H, Ma X, Lei HR, Milton J, Tang W, Jin C, Gao J, Wittrig AM, Archibold EF, Nash JJ, Kenttämaa HI. Polar Effects Control the Gas-Phase Reactivity of para-Benzyne Analogs. Chemphyschem 2018; 19:2839-2842. [PMID: 30203923 DOI: 10.1002/cphc.201800646] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Indexed: 11/05/2022]
Abstract
We report herein a gas-phase reactivity study on a para-benzyne cation and its three cyano-substituted, isomeric derivatives performed using a dual-linear quadrupole ion trap mass spectrometer. All four biradicals were found to undergo primary and secondary radical reactions analogous to those observed for the related monoradicals, indicating the presence of two reactive radical sites. The reactivity of all biradicals is substantially lower than that of the related monoradicals, as expected based on the singlet ground states of the biradicals. The cyano-substituted biradicals show substantially greater reactivity than the analogous unsubstituted biradical. The greater reactivity is rationalized by the substantially greater (calculated) electron affinity of the radical sites of the cyano-substituted biradicals, which results in stabilization of their transition states through polar effects. This finding is in contrast to the long-standing thinking that the magnitude of the singlet-triplet splitting controls the reactivity of para-benzynes.
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Affiliation(s)
- Huaming Sheng
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN 47907, USA
| | - Xin Ma
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN 47907, USA
| | - Hao-Ran Lei
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN 47907, USA
| | - Jacob Milton
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN 47907, USA
| | - Weijuan Tang
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN 47907, USA
| | - Chunfen Jin
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN 47907, USA
| | - Jinshan Gao
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN 47907, USA
| | - Ashley M Wittrig
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN 47907, USA
| | - Enada F Archibold
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN 47907, USA
| | - John J Nash
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN 47907, USA
| | - Hilkka I Kenttämaa
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN 47907, USA
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Vinueza NR, Jankiewicz BJ, Gallardo VA, LaFavers GZ, DeSutter D, Nash JJ, Kenttämaa HI. Reactivity Controlling Factors for an Aromatic Carbon-Centered σ,σ,σ-Triradical: The 4,5,8-Tridehydroisoquinolinium Ion. Chemistry 2015; 22:809-15. [DOI: 10.1002/chem.201502502] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2015] [Revised: 09/27/2015] [Indexed: 11/07/2022]
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