Kinetic Resolution of Secondary Alcohols Using Amidine-Based Catalysts

Li, Ximin; Jiang, Hui; Uffman, Eric W.; Guo, Lei; Zhang, Yuhua; Yang, Xing; Birman, Vladimir B.

doi:10.1021/jo202220x

Cited by 128 publications

(59 citation statements)

References 109 publications

(120 reference statements)

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“…The iodide compound can be preactivated at an o-position to make the dimerization regioselective. The total synthesis of secalonic acid D (105) is illustrated in Scheme 21 [213][214][215][216].…”

Section: Secalonic Acid Dmentioning

confidence: 99%

Marine Natural Products as Models to Circumvent Multidrug Resistance

et al. 2016

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Multidrug resistance (MDR) to anticancer drugs is a serious health problem that in many cases leads to cancer treatment failure. The ATP binding cassette (ABC) transporter P-glycoprotein (P-gp), which leads to premature efflux of drugs from cancer cells, is often responsible for MDR. On the other hand, a strategy to search for modulators from natural products to overcome MDR had been in place during the last decades. However, Nature limits the amount of some natural products, which has led to the development of synthetic strategies to increase their availability. This review summarizes the research findings on marine natural products and derivatives, mainly alkaloids, polyoxygenated sterols, polyketides, terpenoids, diketopiperazines, and peptides, with P-gp inhibitory activity highlighting the established structure-activity relationships. The synthetic pathways for the total synthesis of the most promising members and analogs are also presented. It is expected that the data gathered during the last decades concerning their synthesis and MDR-inhibiting activities will help medicinal chemists develop potential drug candidates using marine natural products as models which can deliver new ABC transporter inhibitor scaffolds.

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Section: Secalonic Acid Dmentioning

confidence: 99%

Marine Natural Products as Models to Circumvent Multidrug Resistance

et al. 2016

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“…However, differentiation between the two enantiomers of u -4 turned out to be very difficult for well-known, venerable catalysts. [30–31] We were pleased that a brief screen of π-methylhistidine-containing peptide catalysts [32] revealed a β-turn motif—Boc-Pmh- d Pro-Aib-Phe-OMe—that allowed for the isolation of starting material u -4 in 74.0:26.0 e.r. and acylation product u -5 with 36.5:63.5 e.r.…”

mentioning

confidence: 99%

A Stereodynamic Redox‐Interconversion Network of Vicinal Tertiary and Quaternary Carbon Stereocenters in Hydroquinone–Quinone Hybrid Dihydrobenzofurans

et al. 2018

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Reversible redox processes involving hydroquinones and quinones are ubiquitous in biological reaction networks, materials science, and catalysis. While extensively studied in intermolecular settings, less is known about intramolecular scenarios. Herein, we report hydroquinone-quinone hybrid molecules that form two-stereocenter dihydrobenzofurans via intramolecular cyclization under thermodynamic control. A π-methylhistidine peptide-catalyzed kinetic resolution allowed us to study the stereodynamic behavior of enantio- and diastereo-enriched dihydrofurans. In the course of this study, it was revealed that a reversible intramolecular redox-interconversion network connects all four possible stereoisomers via inversion of a quaternary carbon stereocenter without achiral intermediates. As a result, these findings on hydroquinone-quinone hybrid molecules provide insights into potential natural origin and synthetic access of the common dihydrobenzofuran motif.

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“…The process was initially studied in chloroform, however, slow deactivation of the catalyst was observed although selectivity remained constant over ten consecutive cycles (see Table S1). The deactivation process can be tentatively attributed to hydrolysis of the intermediate acylisothiouronium species as suggested by Birman, and we reasoned that using the less labile and less toxic anhydrous CH 2 Cl 2 could minimize the deactivation problem without requiring solvent pre‐treatments. As shown in Table , no decrease in catalytic activity or enantioselectivity was observed in a ten‐cycle experiment in this solvent.…”

Section: Resultsmentioning

confidence: 89%

Continuous Flow Preparation of Enantiomerically Pure BINOL(s) by Acylative Kinetic Resolution

et al. 2020

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A polystyrene‐immobilized isothiourea has been applied to the enantioselective acylative kinetic resolution (KR) of monoacylated BINOL(s) with inexpensive isobutyric anhydride in batch and flow. High selectivity values (s=29 at 0 °C) and a remarkable stability of the catalytic system in the operation conditions have been recorded for unsubstituted BINOL. No significant loss of activity/selectivity is recorded after 10 consecutive KR cycles in batch. A continuous flow process has been implemented and operated with a 100 mmol (32.8 g) sample of racemic monoacetylated BINOL in dichloromethane solution in an 84 hours experiment with a packed bed reactor containing 1 g (f=0.37 mmol.g−1) of the functional resin (s=17–21). Residence time can be decreased to 10 min with the same reactor to achieve a conversion of 58% with a selectivity factor s=17 when a more highly functionalized catalyst (f=0.88 mmol.g−1) is used. This translates into a remarkable combined productivity of 5.5 mmolprod ⋅ mmolcat−1 ⋅ h−1.

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Kinetic Resolution of Secondary Alcohols Using Amidine-Based Catalysts

Cited by 128 publications

References 109 publications

Marine Natural Products as Models to Circumvent Multidrug Resistance

Marine Natural Products as Models to Circumvent Multidrug Resistance

A Stereodynamic Redox‐Interconversion Network of Vicinal Tertiary and Quaternary Carbon Stereocenters in Hydroquinone–Quinone Hybrid Dihydrobenzofurans

Continuous Flow Preparation of Enantiomerically Pure BINOL(s) by Acylative Kinetic Resolution

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