Synthesis of Lactams via Isocyanide-Based Multicomponent Reactions

Synthesis ◽  
2020 ◽  
Author(s):  
Shrikant G. Pharande
Keyword(s):  
Natural Products ◽  
Multicomponent Reactions ◽  
Bioactive Molecules ◽  
Wide Range ◽  
Two Component ◽  
Synthetic Intermediates

AbstractLactams are very important heterocycles as a result of their presence in a wide range of bioactive molecules, natural products and drugs, and also due their utility as versatile synthetic intermediates. Due to these reasons, numerous efforts have focused on the development of effective and efficient methods for their synthesis. Compared to conventional two-component reactions, multicomponent reactions (MCRs), particularly isocyanide-based MCRs, are widely used for the synthesis of a range of small heterocycles including lactam analogues. Despite their numerous applications in almost every field of chemistry, as yet there is no dedicated review on isocyanide-based multicomponent reactions (IMCRs) concerning the synthesis of lactams. Therefore, this review presents strategies towards the synthesis of α-, β-, γ-, δ- and ε-lactams using IMCRs or IMCRs/post-transformation reactions reported in the literature between 2000 and 2020.1 Introduction2 Developments in Lactam Synthesis2.1 α-Lactams2.2 β-Lactams2.3 γ-Lactams2.3.1 General γ-Lactams2.3.2 Benzo-Fused γ-Lactams2.3.3 Spiro γ-Lactams2.3.4 α,β-Unsaturated γ-Lactams2.3.5 Polycyclic Fused γ-Lactams2.4 δ-Lactams2.5 ε-Lactams3 Conclusions

scholarly journals From Sea to Skin: Is There a Future for Natural Photoprotectants?

Marine Drugs ◽  
2021 ◽  
Vol 19 (7) ◽  
pp. 379
Author(s):  
Alfonsina Milito ◽  
Immacolata Castellano ◽  
Elisabetta Damiani
Keyword(s):  
Public Health ◽  
Natural Products ◽  
Sun Exposure ◽  
Marine Species ◽  
Bioactive Molecules ◽  
Health Concern ◽  
Skin Damage ◽  
Negative Effects ◽  
Solar Ultraviolet Radiation ◽  
Wide Range

In the last few decades, the thinning of the ozone layer due to increased atmospheric pollution has exacerbated the negative effects of excessive exposure to solar ultraviolet radiation (UVR), and skin cancer has become a major public health concern. In order to prevent skin damage, public health advice mainly focuses on the use of sunscreens, along with wearing protective clothing and avoiding sun exposure during peak hours. Sunscreens present on the market are topical formulations that contain a number of different synthetic, organic, and inorganic UVR filters with different absorbance profiles, which, when combined, provide broad UVR spectrum protection. However, increased evidence suggests that some of these compounds cause subtle damage to marine ecosystems. One alternative may be the use of natural products that are produced in a wide range of marine species and are mainly thought to act as a defense against UVR-mediated damage. However, their potential for human photoprotection is largely under-investigated. In this review, attention has been placed on the molecular strategies adopted by marine organisms to counteract UVR-induced negative effects and we provide a broad portrayal of the recent literature concerning marine-derived natural products having potential as natural sunscreens/photoprotectants for human skin. Their chemical structure, UVR absorption properties, and their pleiotropic role as bioactive molecules are discussed. Most studies strongly suggest that these natural products could be promising for use in biocompatible sunscreens and may represent an alternative eco-friendly approach to protect humans against UV-induced skin damage.

scholarly journals A Review of the Synthetic Strategies toward Dihydropyrrolo[1,2-a]Pyrazinones

Organics ◽  
2021 ◽  
Vol 2 (2) ◽  
pp. 118-141
Author(s):  
Pieterjan Winant ◽  
Tomas Horsten ◽  
Shaiani Gil de Melo ◽  
Flavio Emery ◽  
Wim Dehaen
Keyword(s):  
Natural Products ◽  
Multicomponent Reactions ◽  
Direct Result ◽  
Bioactive Natural Products ◽  
Wide Range ◽  
Privileged Class

Dihydropyrrolo[1,2-a]pyrazinone rings are a class of heterocycles present in a wide range of bioactive natural products and analogues thereof. As a direct result of their bioactivity, the synthesis of this privileged class of compounds has been extensively studied. This review provides an overview of these synthetic pathways. The literature is covered up until 2020 and is organized according to the specific strategies used to construct the scaffold: fusing a pyrazinone to an existing pyrrole, employing a pyrazinone-first strategy, an array of multicomponent reactions and some miscellaneous reactions.

scholarly journals Chiral Alkyl Amine Synthesis via Catalytic Enantioselective Hydroalkylation of Enamides

2020 ◽  
Author(s):  
Deyun Qian ◽  
Srikrishna Bera ◽  
Xile Hu
Keyword(s):  
Natural Products ◽  
Functional Group ◽  
Building Blocks ◽  
Alkyl Halides ◽  
Enantioselective Synthesis ◽  
Mild Conditions ◽  
Drug Molecules ◽  
Alkyl Amines ◽  
Wide Range ◽  
Synthetic Intermediates

Chiral alkyl amines are omnipresent as bio-active molecules and synthetic intermediates. Catalytic and enantioselective synthesis of alkyl amines from readily accessible precursors is challenging. Here we develop a nickel-catalyzed hydroalkylation method to assemble a wide range of chiral alkyl amines from enamides and alkyl halides in high regio- and enantioselectivity. The method works for both non-activated and activated alkyl halides, and is able to produce enantiomerically enriched amines with two minimally differentiated alpha-alkyl substituents. The mild conditions lead to high functional group tolerance, which is demonstrated in the post-product functionalization of many natural products and drug molecules, as well as the synthesis of chiral building blocks and key intermediates to bio-active compounds.

scholarly journals Chiral Alkyl Amine Synthesis via Catalytic Enantioselective Hydroalkylation of Enamides

2020 ◽  
Author(s):  
Deyun Qian ◽  
Srikrishna Bera ◽  
Xile Hu
Keyword(s):  
Natural Products ◽  
Functional Group ◽  
Building Blocks ◽  
Alkyl Halides ◽  
Enantioselective Synthesis ◽  
Mild Conditions ◽  
Drug Molecules ◽  
Alkyl Amines ◽  
Wide Range ◽  
Synthetic Intermediates

Chiral alkyl amines are omnipresent as bio-active molecules and synthetic intermediates. Catalytic and enantioselective synthesis of alkyl amines from readily accessible precursors is challenging. Here we develop a nickel-catalyzed hydroalkylation method to assemble a wide range of chiral alkyl amines from enamides and alkyl halides in high regio- and enantioselectivity. The method works for both non-activated and activated alkyl halides, and is able to produce enantiomerically enriched amines with two minimally differentiated alpha-alkyl substituents. The mild conditions lead to high functional group tolerance, which is demonstrated in the post-product functionalization of many natural products and drug molecules, as well as the synthesis of chiral building blocks and key intermediates to bio-active compounds.

Copper Catalyzed sp3 C-H α-Acetylation

2019 ◽  
Author(s):  
Otome Okoromoba ◽  
Eun Sil Jang ◽  
Claire McMullin ◽  
Thomas Cundari ◽  
Timothy H. Warren
Keyword(s):  
Natural Products ◽  
Dft Studies ◽  
Alkyl Radicals ◽  
Important Chemical ◽  
Alkyl Electrophiles ◽  
Synthetic Intermediates ◽  
Alkylation Reactions

<p>α-substituted ketones are important chemical targets as synthetic intermediates as well as functionalities in in natural products and pharmaceuticals. We report the sp<sup>3</sup> C-H α-acetylation of sp<sup>3</sup> C-H substrates R-H with arylmethyl ketones ArC(O)Me to provide α-alkylated ketones ArC(O)CH<sub>2</sub>R at RT with <sup>t</sup>BuOO<sup>t</sup>Bu as oxidant via copper(I) β-diketiminato catalysts. Proceeding via alkyl radicals R•, this method enables α-substitution with bulky substituents without competing elimination that occurs in more traditional alkylation reactions between enolates and alkyl electrophiles. DFT studies suggest the intermediacy of copper(II) enolates [Cu<sup>II</sup>](CH<sub>2</sub>C(O)Ar) that capture alkyl radicals R• to give R-CH<sub>2</sub>C(O)Ar under competing dimerization of the copper(II) enolate to give the 1,4-diketone ArC(O)CH<sub>2</sub>CH<sub>2</sub>C(O)Ar.</p>

Copper Catalyzed sp3 C-H α-Acetylation

2019 ◽  
Author(s):  
Otome Okoromoba ◽  
Eun Sil Jang ◽  
Claire McMullin ◽  
Thomas Cundari ◽  
Timothy H. Warren
Keyword(s):  
Natural Products ◽  
Dft Studies ◽  
Alkyl Radicals ◽  
Important Chemical ◽  
Alkyl Electrophiles ◽  
Synthetic Intermediates ◽  
Alkylation Reactions

<p>α-substituted ketones are important chemical targets as synthetic intermediates as well as functionalities in in natural products and pharmaceuticals. We report the sp<sup>3</sup> C-H α-acetylation of sp<sup>3</sup> C-H substrates R-H with arylmethyl ketones ArC(O)Me to provide α-alkylated ketones ArC(O)CH<sub>2</sub>R at RT with <sup>t</sup>BuOO<sup>t</sup>Bu as oxidant via copper(I) β-diketiminato catalysts. Proceeding via alkyl radicals R•, this method enables α-substitution with bulky substituents without competing elimination that occurs in more traditional alkylation reactions between enolates and alkyl electrophiles. DFT studies suggest the intermediacy of copper(II) enolates [Cu<sup>II</sup>](CH<sub>2</sub>C(O)Ar) that capture alkyl radicals R• to give R-CH<sub>2</sub>C(O)Ar under competing dimerization of the copper(II) enolate to give the 1,4-diketone ArC(O)CH<sub>2</sub>CH<sub>2</sub>C(O)Ar.</p>

Indium Bromide-catalyzed Unprecedented Hydrogenolysis: A Novel One-Pot Synthesis of Per-O-Acetylated β-carboxymethyl O and S-glycosides

2020 ◽  
Vol 24 (8) ◽  
pp. 900-908
Author(s):  
Ram Naresh Yadav ◽  
Amrendra K Singh ◽  
Bimal Banik
Keyword(s):  
Asymmetric Synthesis ◽  
Chiral Auxiliary ◽  
Bioactive Molecules ◽  
One Pot ◽  
Enantiomerically Pure ◽  
Stereoselective Glycosylation ◽  
One Pot Synthesis ◽  
Wide Range

Numerous O (oxa)- and S (thia)-glycosyl esters and their analogous glycosyl acids have been accomplished through stereoselective glycosylation of various peracetylated bromo sugar with benzyl glycolate using InBr3 as a glycosyl promotor followed by in situ hydrogenolysis of resulting glycosyl ester. A tandem glycosylating and hydrogenolytic activity of InBr3 has been successfully investigated in a one-pot procedure. The resulting synthetically valuable and virtually unexplored class of β-CMGL (glycosyl acids) could serve as an excellent potential chiral auxiliary in the asymmetric synthesis of a wide range of enantiomerically pure medicinally prevalent β-lactams and other bioactive molecules of diverse medicinal interest.

scholarly journals Photocatalytic three-component asymmetric sulfonylation via direct C(sp3)-H functionalization

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Shi Cao ◽  
Wei Hong ◽  
Ziqi Ye ◽  
Lei Gong
Keyword(s):  
Asymmetric Catalysis ◽  
Organic Synthesis ◽  
Photochemical Reaction ◽  
Low Cost ◽  
Bioactive Molecules ◽  
Atom Economy ◽  
Mild Conditions ◽  
Wide Range ◽  
Unsaturated Carbonyl Compound ◽  
Direct Functionalization

AbstractThe direct and selective C(sp3)-H functionalization of cycloalkanes and alkanes is a highly useful process in organic synthesis owing to the low-cost starting materials, the high step and atom economy. Its application to asymmetric catalysis, however, has been scarcely explored. Herein, we disclose our effort toward this goal by incorporation of dual asymmetric photocatalysis by a chiral nickel catalyst and a commercially available organophotocatalyst with a radical relay strategy through sulfur dioxide insertion. Such design leads to the development of three-component asymmetric sulfonylation involving direct functionalization of cycloalkanes, alkanes, toluene derivatives or ethers. The photochemical reaction of a C(sp3)-H precursor, a SO2 surrogate and a common α,β-unsaturated carbonyl compound proceeds smoothly under mild conditions, delivering a wide range of biologically interesting α-C chiral sulfones with high regio- and enantioselectivity (>50 examples, up to >50:1 rr and 95% ee). This method is applicable to late-stage functionalization of bioactive molecules, and provides an appealing access to enantioenriched compounds starting from the abundant hydrocarbon compounds.

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