Photo-On-Demand Synthesis of α-Amino Acid <i>N</i>-Carboxyanhydrides with Chloroform

Sugimoto, Toshiyuki; Kuwahara, Tomoya; Liang, Fengying; Wang, Huirong; Tsuda, Akihiko

doi:10.1021/acsomega.2c05299

Cited by 9 publications

(3 citation statements)

References 44 publications

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“…To ensure safe use of this reaction, we then developed "in situ" photo-ondemand phosgenation reactions, which required the design and construction of batch and flow reaction systems [25][26][27][28][29][30][31][32][33][34]. We have successfully applied this photo-ondemand phosgenation reaction on a practical scale for most common phosgenation reactions, such as the syntheses of chloroformates [25,26], carbonate esters [28,29], PCs [28], isocyanates [30], Vilsmeier reagents [27], acyl chlorides [25], and α-amino acid N-carboxyanhydrides (NCAs) [32] (Fig. 3).…”

Section: Introductionmentioning

confidence: 99%

In situ photo-on-demand phosgenation reactions with chloroform for syntheses of polycarbonates and polyurethanes

Tsuda

2023

Polym J

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Phosgene is an important carbonyl source for industrial production of polycarbonates (PCs) and polyurethanes (PUs). However, since it is highly toxic, alternative compounds and/or new phosgenation reactions have been explored for safety reasons. Given this background, we found a novel photochemical reaction enabling the synthesis of phosgene from chloroform. Subsequently, we developed new phosgenation reactions and reaction systems, and the key objective was “safe application” to organic synthesis. This focus review reports our recent use of in situ photo-on-demand phosgenations of alcohols and amines in synthesizing PC, PU, and their precursors, such as chloroformates, carbonate esters, and diisocyanates, in batch reaction systems, which are preferable for laboratory or small-scale industrial syntheses. We believe that the present reactions have advantages over conventional phosgenation reactions, especially in terms of safety and environmental impacts, and are expected to make positive contributions to practical organic syntheses in both academia and industry.

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Section: Introductionmentioning

confidence: 99%

In situ photo-on-demand phosgenation reactions with chloroform for syntheses of polycarbonates and polyurethanes

Tsuda

2023

Polym J

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“…The reaction occurred efficiently in a short time upon irradiation of CHCl 3 under O 2 bubbling using UV-C light from a low-pressure mercury lamp (LPML). We then developed photo-on-demand in situ phosgenation reactions for synthesizing a variety of organic chemicals and polymers with CHCl 3 solutions containing both a substrate and an organic base [Scheme , reaction (c)]. − Although alcohols such as EtOH serve to stabilize CHCl 3 , and the organic bases and solvents absorb UV-C light, , the phosgenation products were obtained in high yields through in situ reactions of the substrates and COCl 2 generated from CHCl 3 . These results indicated that the photochemical oxidation of CHCl 3 occurred not only in the liquid phase but also in the gas phase.…”

Section: Introductionmentioning

confidence: 99%

Photo-on-Demand In Situ Phosgenation Reactions That Cross Three Phases of a Heterogeneous Solution of Chloroform and Aqueous NaOH

et al. 2023

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Here, we report a novel photo-on-demand in situ phosgenation reaction that crosses three phases of a heterogeneous solution of chloroform (CHCl3) and aqueous NaOH containing an aryl alcohol or amine. This reaction system enables the safe, convenient, and inexpensive synthesis of carbonate esters, polycarbonates, and N-substituted ureas from aryl alcohols, aryl diols, and primary/secondary amines, respectively, on a practical scale and with good yield. The photochemical oxidation of CHCl3 to phosgene (COCl2) occurs upon irradiation with UV light from a low-pressure mercury lamp of both the gas and liquid phases of the reaction system under O2 bubbling of the vigorously stirred sample solution. The following reaction mechanisms are suggested: The aryl alcohol reacts in situ with the generated COCl2 at the interfaces of the organic/aqueous phases and aqueous/gas phases, in competition with the decomposition of COCl2 due to hydrolysis. Nucleophilicity and hydrophilicity are enhanced by the formation of aryl alkoxide ion through the reaction with NaOH, whereas the reaction of amine proceeds through neutralization of the generated HCl by the aqueous NaOH.

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“…95 More recently, they have also reported CHCl 3 oxygenation under visible-light irradiation using trace amounts of Cl 2 as an initiator. 96,97 In addition, our research group has developed a CHCl 3 oxygenation reaction via the photoactivation of ClO 2 (Scheme 20). 98 Carbamoyl chlorides were synthesised from a wide substrate range by the phosgenation of amines under visible-light irradiation (l 4 400 nm) as ClO 2 exhibits a strong absorption band in the visible-light region (Fig.…”

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confidence: 99%