2023

6) C-O結合の均等開裂を伴うアルコールのone-pot官能基化
One─pot Functionalization of Alcohols via Homolytic Cleavage of their C─O Bonds

森山将吾
有機合成化学協会誌, 2023 年 81 巻 9 号 p. 892-894
DOI:10.5059/yukigoseikyokaishi.81.892

Abstract: The Barton-McCombie type reaction usually requires prefunctionalization of the hydroxy group of alcohols to induce deoxygenative generation of alkyl radicals. In recent years, synthetic reactions, wherein reactive intermediates generated in situ induce homolytic C-O bond cleavage of alcohols, have been reported. The present short review will discuss recent progress in radical alkylation using alcohols as alkyl radical sources.

5) Lipase/H2SO4-Cocatalyzed Dynamic Kinetic Resolution of Alcohols in Pickering Emulsion
Jihoon Moon, Takusho Kin, Karin Mizuno, Shuji Akai, Kyohei Kanomata
ChemCatChem, 2023, 15, e202300878.
DOI:10.1002/cctc.202300878

Abstract: This study reports the first chemoenzymatic dynamic kinetic resolution (DKR) of racemic sec-alcohols by simultaneously using immobilized lipase and aqueous sulfuric acid as catalysts for kinetic resolution and racemization, respectively. The nanoparticle-stabilized phase separation in a Pickering emulsion enabled the use of these inherently incompatible catalysts in a single vessel. The racemization reaction in the aqueous sulfuric acid solution significantly suppressed the dehydrative side reactions that form alkenes and dimeric ethers, which are often observed in racemization using Brønsted/Lewis acids or oxovanadium compounds in organic solvents. The efficacy of the Pickering emulsion was confirmed by the significantly lower catalytic performance in DKR without emulsification. This method achieved high yields and high optical purities in the production of a wide range of sec-alcohols.

4) Heterogeneously Catalyzed Aromatic Reduction
Yoshinari Sawama, Kazuho Ban, Hironao Sajiki
Industrial Arene Chemistry: Markets, Technologies, Sustainable Processes and Cases Studies of Aromatic Commodities (Chapter 30), Jacques Mortier, Wiley‐VCH GmbH, 2, 883-918 (2023)
DOI:10.1002/9783527827992.ch30

3) Unprecedented Regioselective Deuterium-Incorporation of Alkyltrimethylammonium Chlorides and Raman Analysis
Yoshinari Sawama, Takumi Matsuda, Shogo Moriyama, Kazuho Ban, Hiroyoshi Fujioka, Mako Kamiya, Jingwen Shou, Yasuyuki Ozeki, Shuji Akai, Hironao Sajiki
Asian J. Org., Chem. 2023, in press.
DOI:10.1002/ajoc.202200710

Abstract: Alkyltrimethylammonium chlorides (ATACs) are widely utilized as cationic surfactants in various scientific fields. Furthermore, deuterium-incorporated compounds can be powerful tools for elucidating the complicated morphologies of molecules with high molecular weights. Dodecyltrimethylammonium chloride (DTAC), as a representative ATAC, underwent the regioselective multi-deuteration of alkylamine moiety, except for α and β-positions. Deuteration was performed under Pt/C and Ru/C-catalyzed conditions in 2-PrOH and D2O. The stimulated Raman scattering (SRS) revealed the specific signals of multi-deuterated DTAC in the silent region.

2) 機械学習で予測するC(sp3)–H官能基化反応の位置選択性
鹿又喬平
ファルマシア, 2023, 59, 5, 432
DOI:10.14894/faruawpsj.59.5_432

新規な基質の反応位置・立体選択性などを予測するツールとして,機械学習を利用する試みが活発化している.C–H結合の官能基化反応では,配向基を用いず,触媒のみによって制御される反応の位置選択性を経験的に予測することは難しい.最近Boniらは,二核ロジウム錯体を触媒とするC(sp3)–H変換反応について,機械学習による位置選択性の予測モデルを報告したので紹介する.
なお,本稿は下記の文献に基づいて,その研究成果を紹介するものである.
Boni Y. T. et al., J. Am. Chem. Soc., 144, 15549–15561 (2022).

1) Chemoenzymatic Dynamic Kinetic Resolution of Alcohols
Kyohei Kanomata, Shuji Akai
Science of Synthesis, 2022/4: Dynamic Kinetic Resolution (DKR) and Dynamic Kinetic Asymmetric Transformations (DYKAT): Bäckvall, J.-E., Ed.; Thieme: Stuttgart (2023), Vol. 1, p 181–217.
DOI: 10.1055/sos-SD-237-00069

Abstract: Chemoenzymatic dynamic kinetic resolution is one of the simplest and most reliable methods to obtain optically pure alcohol derivatives from racemates. For this purpose, hydrolases, especially lipases, have been widely used in the enantioselective esterification processes, and a variety of racemization catalysts with high catalytic efficiency and compatibility with lipases have been developed. This review introduces chemoenzymatic DKR of alcohols based on the category of racemization catalysts. DKR of axially chiral hydroxybiaryls and the use of engineered lipases to obtain opposite enantiomers, as well as the synthetic applications of the DKR products, are also discussed.