Photochemical synthesis of acetals utilizing Schreiner's thiourea as the catalyst

Spiliopoulou, Nikoleta; Nikitas, Nikolaos F.; Kokotos, Christoforos G.

doi:10.1039/d0gc01135e

Cited by 45 publications

(28 citation statements)

References 82 publications

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“…[16] Interestingly, very recently Kokotos employed Schreiner's thiourea as a catalyst in a photochemical synthesis of acetals without using a photosensitizer and in which oxygen is not involved. [17] These reports underline the versatility and multi-faceted role of thiourea in photochemical reactions and its role in our photocatalyzed twostep domino reaction (amine oxidation/vinylogous Mannich) is apparently not trivial.…”

Section: Resultsmentioning

confidence: 92%

Visible Light-driven Metal-free C–H Functionalization: Access to New Bioactive Tetrahydroisoquinoline-Butenolide Hybrids via Domino Amine Oxidation/Vinylogous Mannich Reaction

Kersting

Kuhn

Anokhin

et al. 2021

Preprint

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An efficient metal-free visible light-driven two-step domino reaction towards new bioactive tetrahydroisoquinoline-butenolide hybrid compounds was developed for the first time. Combination of fluorescein as photosensitizer and thiourea as an additive was found to be the most effective way to promote an aerobic amine oxidation/vinylogous Mannich domino reaction sequence with yields up to 97% for a broad substrate scope. While fluorescein without thiourea additive gave product in 84% yield, it was even observed that thiourea in absence of fluorescein is also able to promote formation of product with good yield of 75%, which is explained by a potential role of thiourea as an electron-transfer mediator in light-induced amine oxidation. Both experimental and computational evidence supported the crucial role of singlet oxygen in the developed C–H functionalization reaction. In addition, in vitro studies of tetrahydroisoquinoline-butenolide hybrid compounds demonstrated their high antischistosomal and anti-cancer activities.

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Section: Resultsmentioning

confidence: 92%

Visible Light-driven Metal-free C–H Functionalization: Access to New Bioactive Tetrahydroisoquinoline-Butenolide Hybrids via Domino Amine Oxidation/Vinylogous Mannich Reaction

Kersting

Kuhn

Anokhin

et al. 2021

Preprint

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“…Recently, Jacobsen, Stephenson and co‐workers reported an oxidative C−H functionalization of tetrahydroisoquinolines towards β‐amino esters via a combination of photoredox reaction, using a ruthenium complex as photocatalyst, and subsequent anion‐binding organocatalysis, using thiourea [20] . Interestingly, very recently, Kokotos employed Schreiner's thiourea as a catalyst in a photochemical synthesis of acetals without using a photosensitizer and in which oxygen is not involved [21] . These reports underline the versatility and multi‐faceted role of thiourea in photochemical reactions and its role in our photocatalyzed two‐step domino reaction (amine oxidation/vinylogous Mannich) is apparently not trivial.…”

Section: Resultsmentioning

confidence: 99%

Visible‐Light‐Driven Metal‐Free C−H Functionalization: Access to New Bioactive Tetrahydroisoquinoline‐Butenolide Hybrids via Domino Amine Oxidation/Vinylogous Mannich Reaction**

et al. 2022

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An efficient metal‐free visible‐light‐driven two‐step domino reaction towards new bioactive tetrahydroisoquinoline‐butenolide hybrid compounds was developed for the first time. The combination of fluorescein as photosensitizer and thiourea as an additive was found to be the most effective way to promote an aerobic amine oxidation/vinylogous Mannich domino reaction sequence with yields up to 97 % for a broad substrate scope. Both experimental and computational evidence supported the crucial role of singlet oxygen in the developed C−H functionalization reaction. Furthermore, the data suggest that thiourea is essential due to its ability to act as an electron‐transfer mediator and/or scavenger of reactive oxygen species. In addition, in vitro studies of tetrahydroisoquinoline‐butenolide hybrid compounds demonstrated their high antischistosomal and anti‐cancer activities.

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“…85 A green photochemical protocol was deployed using Eosin Y 86 with green LED, thioxanthenone, 87 Schreiner's thiourea as photocatalyst and household lamps as a light source. 88 A range of aromatic and aliphatic aldehydes was converted into acetals in quantitative high yields (Figure 5).…”

Section: Recent Green Synthesis Of Acetalmentioning

confidence: 99%

A Concise Review on Synthesis of Acetal and Recent Advances

Firke¹

2022

YMER

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Photochemical synthesis of acetals utilizing Schreiner's thiourea as the catalyst

Abstract: Schreiner's thiourea activating aldehydes in photochemical reactions.

Cited by 45 publications

References 82 publications

Visible Light-driven Metal-free C–H Functionalization: Access to New Bioactive Tetrahydroisoquinoline-Butenolide Hybrids via Domino Amine Oxidation/Vinylogous Mannich Reaction

Visible Light-driven Metal-free C–H Functionalization: Access to New Bioactive Tetrahydroisoquinoline-Butenolide Hybrids via Domino Amine Oxidation/Vinylogous Mannich Reaction

Visible‐Light‐Driven Metal‐Free C−H Functionalization: Access to New Bioactive Tetrahydroisoquinoline‐Butenolide Hybrids via Domino Amine Oxidation/Vinylogous Mannich Reaction**

A Concise Review on Synthesis of Acetal and Recent Advances

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