Synthesis of Enantioenriched β-Aryl-β-aryloxy Esters via Sequential Photoisomerization and Enantioselective Hydrogenation

Swift, Elizabeth C.; Shekhar, Shashank; Kotecki, Brian J.

doi:10.1021/acs.orglett.0c01508

Cited by 5 publications

(4 citation statements)

References 32 publications

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“…Swift and co-workers have devised an elegant, stereoconvergent process that subjects the mixture of geometric isomers to a photocatalyst to generate the E -isomer predominantly prior to reduction (Scheme ). This strategy enriches the alkene isomer ratio from ∼1:4 to ∼20:1 (e.g., 62 – 64 ). The process occurs under blue light irradiation (459 nm) in the presence of minute amounts of [Ir(ppy) 2 (dtbbpy)]PF 6 (0.05 mol %).…”

Section: Geometric Isomerization Of Simple Alkenes Via Selective Ener...mentioning

confidence: 99%

Advances in theE → ZIsomerization of Alkenes Using Small Molecule Photocatalysts

et al. 2021

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Geometrical E → Z alkene isomerization is intimately entwined in the historical fabric of organic photochemistry and is enjoying a renaissance (Roth et al. Angew. Chem., Int. Ed. Engl. 1989 28, 1193–1207). This is a consequence of the fundamental stereochemical importance of Z-alkenes, juxtaposed with frustrations in thermal reactivity that are rooted in microscopic reversibility. Accessing excited state reactivity paradigms allow this latter obstacle to be circumnavigated by exploiting subtle differences in the photophysical behavior of the substrate and product chromophores: this provides a molecular basis for directionality. While direct irradiation is operationally simple, photosensitization via selective energy transfer enables augmentation of the alkene repertoire to include substrates that are not directly excited by photons. Through sustained innovation, an impressive portfolio of tailored small molecule catalysts with a range of triplet energies are now widely available to facilitate contra-thermodynamic and thermo-neutral isomerization reactions to generate Z-alkene fragments. This review is intended to serve as a practical guide covering the geometric isomerization of alkenes enabled by energy transfer catalysis from 2000 to 2020, and as a logical sequel to the excellent treatment by Dugave and Demange (Chem. Rev. 2003 103, 2475–2532). The mechanistic foundations underpinning isomerization selectivity are discussed together with induction models and rationales to explain the counterintuitive directionality of these processes in which very small energy differences distinguish substrate from product. Implications for subsequent stereospecific transformations, application in total synthesis, regioselective polyene isomerization, and spatiotemporal control of pre-existing alkene configuration in a broader sense are discussed.

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Section: Geometric Isomerization Of Simple Alkenes Via Selective Ener...mentioning

confidence: 99%

Advances in theE → ZIsomerization of Alkenes Using Small Molecule Photocatalysts

et al. 2021

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“…In 2020, the rhodium‐catalyzed enantioselective hydrogenation of esters 9 employing commercially available Josiphos ligand L12 was described by Swift and co‐workers (Scheme 7). [16] The enantioselective hydrogenation achieved a conversion rate of >99.9 % within 4 hours under the easily expandable pressure of H 2 (8 atm), with only 0.05 mol % [Rh(NBD) 2 ]BF 4 and 0.05 mol % Josiphos ligand L12 for most α,β‐unsaturated esters. The hydrogenated products 10 were isolated in up to 96 % yields with up to 97 % ee.…”

Section: Asymmetric Addition To C(sp2)‐c(sp2) Bondsmentioning

confidence: 98%

Bisphospholane Josiphos‐type Ligands in Rhodium Asymmetric Catalysis

Zhang

2023

Chemistry An Asian Journal

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Asymmetric catalysis has become a universal and powerful method for constructing chiral compounds. In rhodium asymmetric catalysis, bisphospholane Josiphos‐type ligands and their rhodium complexes are receiving increasing attention. This review provides comprehensive information on the bisphospholane Josiphos‐type ligands in rhodium asymmetric catalysis. The scope of the literature covers from 2013 to now. The application of bisphospholane Josiphos‐type ligands in rhodium asymmetric catalysis is summarized as follows: (i) asymmetric addition to C(sp2)‐C(sp2) bonds, (ii) asymmetric addition to C(sp2)‐C(sp) bonds of allenes, (iii) asymmetric hydrogenation of C(sp2)‐N bonds, C(sp2)‐O bonds and pyridinium salts, and (iv) asymmetric silanization of C‐H and O‐H bonds.

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“…AbbVie developed a photoisomerization reaction as part of a sequential isomerization/enantioselective hydrogenation process to prepare β-aryl-β-aryloxy carboxylic esters (Scheme 126). 367 The use of a laser diode as light source was found to be more efficient than more established LED strip or Kessil lamp setups, with the laser diode facilitating isomerization to almost 90% of the E-isomer in approximately 1 h. The Class IV laser (λ max = 450 nm) was used in conjunction with a heat sink to prevent overheating and the current was adjusted to give an output power of 2 W (maximum 6 W). A lens was used to disperse the beam over the area of the reaction vial ensuring uniformity of light across the reaction mixture and reducing the risk associated with high-powered laser beams.…”

Section: Batch Reactorsmentioning

confidence: 99%

“…They reported a procedure for the synthesis of β-aryl-β-aryloxy esters via a sequential photoisomerization and enantioselective hydrogenation (Scheme 144). 367 The use of a high-powered laser in combination with an iridium triplet sensitizer was beneficial in terms of reaction rate when compared to more conventional blue LED light sources. Scale-up was performed using a small jacketed vessel as a temperature-controlled reactor, with a 25 W laser giving 15 g of product 161 (96:4 E/Z ratio) in 16 h.…”

Section: Scale-up In Batchmentioning

confidence: 99%

Photocatalysis in the Life Science Industry

et al. 2021

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In the pursuit of new pharmaceuticals and agrochemicals, chemists in the life science industry require access to mild and robust synthetic methodologies to systematically modify chemical structures, explore novel chemical space, and enable efficient synthesis. In this context, photocatalysis has emerged as a powerful technology for the synthesis of complex and often highly functionalized molecules. This Review aims to summarize the published contributions to the field from the life science industry, including research from industrial-academic partnerships. An overview of the synthetic methodologies developed and strategic applications in chemical synthesis, including peptide functionalization, isotope labeling, and both DNA-encoded and traditional library synthesis, is provided, along with a summary of the state-of-the-art in photoreactor technology and the effective upscaling of photocatalytic reactions.

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Synthesis of Enantioenriched β-Aryl-β-aryloxy Esters via Sequential Photoisomerization and Enantioselective Hydrogenation

Cited by 5 publications

References 32 publications

Advances in theE → ZIsomerization of Alkenes Using Small Molecule Photocatalysts

Advances in theE → ZIsomerization of Alkenes Using Small Molecule Photocatalysts

Bisphospholane Josiphos‐type Ligands in Rhodium Asymmetric Catalysis

Photocatalysis in the Life Science Industry

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