Gillesds

The regioselective ring-opening of 1,2- and 1,3-sulfamidates with fluorine anion is reported. Construction of monofluoro-substituted amines and amino acid derivatives is realized by using inexpensive potassium fluoride (KF). The monofluorination process only needs 35 minutes under heating, which will be an attractive new route for the synthesis of the PET fluorine-18 radiotracer.

Abstract

The regioselective ring-opening of 1,2- and 1,3-sulfamidates with fluorine anion is reported. Direct construction of monofluoro-substituted amines and amino acid derivatives using inexpensive and easily available potassium fluoride (KF). The monofluorination process only needs 35 minutes under heating, which will be an attractive route for the synthesis of the PET fluorine-18 radiotracer. The application of the product can be extended to the construction of fluorinated polypeptides after simple deprotection treatment.

Nature, Published online: 26 January 2022; doi:10.1038/d41586-022-00175-7

Synlett
DOI: 10.1055/s-0041-1737792

The use of low-energy deep-red (DR) and near-infrared (NIR) light to excite chromophores enables catalysis to ensue across barriers such as materials and tissues. Herein, we report the detailed photophysical characterization of a library of OsII polypyridyl photosensitizers that absorb low-energy light. By tuning ligand scaffold and electron density, we access a range of synthetically useful excited state energies and redox potentials.1 Introduction1.1 Scope1.2 Measuring Ground-State Redox Potentials1.3 Measuring Photophysical Properties1.4 Synthesis of Osmium Complexes2 Properties of Osmium Complexes2.1 Redox Potentials of Os(L)2-Type Complexes2.2 Redox Potentials of Os(L)3-Type Complexes2.3 UV/Vis Absorption and Emission Spectroscopy3 Conclusions
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Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, Germany

Article in Thieme eJournals:
Table of contents  |  Abstract  |  Full text

Publication date: 13 January 2022

Source: Chem, Volume 8, Issue 1

Author(s): Mihrimah Ozkan, Amir-Ali Akhavi, William C. Coley, Ruoxu Shang, Yi Ma

A cooperative catalytic mechanism merging the reductive-quenching photocatalytic cycle (Ir^III−*Ir^III−Ir^II−Ir^III) and the copper catalytic cycles (Cu^I−Cu^II−Cu^III−Cu^I) has proven more favorable than the single copper catalysis in C(sp³)−N bond construction. For the dual catalysis, the photocatalyst plays as a “springboard” role, matching better the energy level of Ir^III/Cu^I and Cu^I/substrates, which promotes the single electron transfer rate.

Abstract

Photoredox-mediated dual metal catalysis has been considered as a more efficient method for cross-coupling reactions than single metal catalysis, however, the nature of the significant difference is still unclear. In this work, theoretical research into the decarboxylative C(sp³)−N couplings by Ir^III/Cu^I metallaphotoredox catalysis has been performed by density functional theory (DFT) calculations. A cooperative catalysis mechanism merging the photocatalytic cycle (Ir^III−*Ir^III−Ir^II−Ir^III) and the copper catalytic cycle (Cu^I−Cu^II−Cu^III−Cu^I) has more advantages. For the dual catalysis, the photocatalyst plays a “springboard” role in matching better the energy levels of Ir^III/Cu^I and Cu^I/substrates, which could improve the single electron transfer rate. Moreover, exogenous bases could adjust the proton transfer process and decrease the energy barrier of the rate-determining step to achieve the regioselective monofunctionalization. These theoretical insights could contribute to a deeper understanding of the nature of the photocatalytic decarboxylation reaction and to further developing new cross-coupling reactions.

C₃N₃-Py-P₃/TEB, as a superior organocatalyst toward copolymerization of CO₂ with different epoxides, has a metal-free nature, exhibits high efficiency and selectivity, can be used under ambient conditions, and synthesizes diverse CO₂-PC products.

Abstract

Organophosphazenes combined with triethylborane (TEB) were selected as binary organocatalyts for the copolymerization of CO₂ and epoxides. Both the activity and selectivity were highly dependent on the nature of phosphazenes. 2,4,6-Tris[tri(1-pyrrolidinyl)-iminophosphorane]-1,3,5-triazine (C₃N₃-Py-P₃) with a relatively low basicity (pK _a=26.5 in CD₃CN) and a bulky molecular size (φ=1.3 nm) exhibited an unprecedented efficiency (TON up to 12240) and selectivity (>99 % polymer selectivity and >99 % carbonate linkages) toward copolymerization of CO₂ and cyclohexene oxide (CHO), and produced CO₂-based polycarbonates (CO₂-PCs) with high molar masses (M _n up to 275.5 kDa) at 1 MPa of CO₂ and 80 °C. Surprisingly, this binary catalytic system achieved efficient CO₂/CHO copolymerization with TOF up to 95 h⁻¹ at 1 atm pressure and room temperature.

Even a gifted musician needs a good instrument to present his/her talent in the best possible light. In the same way, organic and medicinal chemists require good synthetic tools to construct their molecules reliably and conveniently. Organoboron compounds have provided such an opportunity for many decades; nevertheless, they are currently receiving increasing attention. This is especially true for saturated boronic derivatives that are widely used as building blocks either to introduce a boron-containing moiety into a potential drug molecule or to create new C(sp³)−C/C(sp³)-heteroatom bonds with enormous efficiency. In their Review on page 15277 ff, Volochnyuk, Gorlova, and Grygorenko cover both of these applications, as well as numerous synthetic approaches to the title compounds.

The aldol-type reaction became one of the forefathers of C−C bond formation reactions. Advancements in the synthetic methodology resulted in the development of chemo-, regio-, and stereoselective processes. This Review focuses on reductive aldol-type alkylation methods implemented to the synthesis of ten approved drug substances. Furthermore, retrosynthetic analysis demonstrates that other active pharmaceutical ingredients could be obtained via reductive Aldol-type reactions. For more information, see the Review by S. Runikhina et al. on page 15327 ff.