<i>N</i>‐Phosphinyl Phosphoramide—A Chiral Brønsted Acid Motif for the Direct Asymmetric N,O‐Acetalization of Aldehydes

Vellalath, Sreekumar; Čorić, Ilija; List, Benjamin

doi:10.1002/ange.201005347

Cited by 46 publications

(8 citation statements)

References 45 publications

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“…Although phosphoric acids were successful in enantioselective synthesis of N,N-aminals, they failed in promoting direct N,O-acetalization between 2-hydroxybenzamide 84 and aldehydes 25 with good enantioselectivity.I ndeed, the reactionr equired the use of N-phosphinyl phosphoramide NPA2 to pro-ceed efficiently (Scheme 19). [51] The authors rationalized these results by ah igherr igidity of the chiral cavity.T his originalr eaction became ar eal synthetic tool since it was appliedt ot he synthesis of analgesic (R)-chlorothenoxazine 85 a.T he target was obtained in 80 %y ield but with ad isappointing7 2% ee. Nonetheless, the enantiopurity was improved to be 93 % ee due to the recrystallization step.…”

Section: C-x Bond Formations By Enantioselective Nucleophilic Additiomentioning

confidence: 94%

Enantioselective Brønsted Acid Catalysis as a Tool for the Synthesis of Natural Products and Pharmaceuticals

Merad

Lalli

Bernadat³

et al. 2017

Chemistry A European J

157

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Synthesis of biologically active molecules (whether at laboratory or industrial scale) remains a highly appealing area of modern organic chemistry. Nowadays, the need to access original bioactive scaffolds goes together with the desire to improve synthetic efficiency, while reducing the environmental footprint of chemical activities. Long neglected in the field of total synthesis, enantioselective organocatalysis has recently emerged as an environmentally friendly and indispensable tool for the construction of relevant bioactive molecules. Notably, enantioselective Brønsted acid catalysis has offered new opportunities in terms of both retrosynthetic disconnections and controlling stereoselectivity. The present report attempts to provide an overview of enantioselective total or formal syntheses designed around Brønsted acid-catalyzed transformations. To demonstrate the versatility of the reactions promoted and the diversity of the accessible motifs, this Minireview draws a systematic parallel between methods and retrosynthetic analysis. The manuscript is organized according to the main reaction types and the nature of newly-formed bonds.

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Section: C-x Bond Formations By Enantioselective Nucleophilic Additiomentioning

confidence: 94%

Enantioselective Brønsted Acid Catalysis as a Tool for the Synthesis of Natural Products and Pharmaceuticals

Merad

Lalli

Bernadat³

et al. 2017

Chemistry A European J

157

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“…There are various reaction systems reported for the synthesis of hemiaminals, such as dicyclohexylboron chloride‐triethylamine system for coupling of amide and aldehyde, polyvalent iodine reagent oxidation systems, phosphoric acid catalysed addition of alcohol to N‐acyl imines, the Pd‐catalysed C−N coupling reaction, titanium ethoxide catalyzed coupling of amide and aldehyde, et al ,. Among those methodologies, nucleophilic addition of alkoxyl group to the imine is one of the typical methods for the synthesis of hemiaminals ,, ,…”

Section: Figurementioning

confidence: 99%

Visible‐Light‐Driven Photochemical Activation of sp³ C−H Bond for Hemiaminal Formation

Zhang

Savateev

et al. 2018

Asian J Org Chem

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Photochemical synthesis of organic chemicals has attracted a massive revitalized research interest. Herein, a metal-free photochemical system with carbon tetrabromide (CBr 4 ) is developed for the synthesis of hemiaminal compounds. In this reaction system, the sp 3 CÀ H bond of the N-alkyl group in the amide is photochemically activated, producing an ionic iminium species. The hemiaminal compounds are produced by nucleophilic attack of the iminium ion by alcohol in the presence of base. This photochemical conversion system shows high yield and broad substrate scope.

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“…Noteworthy examples are Povarov reactions, O-alkylations, Pictet-Spengler reactions or benzidine rearrangement [73][74][75][76]. Chiral BA have shown particularly successful performances in the acetalisation reaction [77][78][79]. In 2005, Antilla et al reported about the amidation of imines, which consists of a N,N-acetalisation.…”

Section: Brønsted Acid Catalysismentioning

confidence: 99%

Organocatalysts for enantioselective synthesis of fine chemicals: definitions, trends and developments

Federsel¹

2014

ScienceOpen Research

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Organocatalysis, that is the use of small organic molecules to catalyse organic transformations, has been included among the most successful concepts in asymmetric catalysis and it has been used for the enantioselective construction of C-C, C-N, C-O, C-S, C-P, and C-halide bonds. Since the seminal works in early 2000, the scientific community has been paying an ever-growing attention to the use of organocatalysts for the synthesis, with high yields and remarkable stereoselectivities, of optically active fine chemicals of interest for the pharmaceutical industry. A brief overview is here presented about the two main classes of substrate activation by the catalyst: covalent organocatalysis and non-covalent organocatalysis, with a more stringent focus on some recent outcomes in the field of the latter and of hydrogen-bond-based catalysis. Finally, some successful examples of heterogenisation of organocatalysts are also discussed, in the view of a potential industrial exploitation.

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N‐Phosphinyl Phosphoramide—A Chiral Brønsted Acid Motif for the Direct Asymmetric N,O‐Acetalization of Aldehydes

Cited by 46 publications

References 45 publications

Enantioselective Brønsted Acid Catalysis as a Tool for the Synthesis of Natural Products and Pharmaceuticals

Enantioselective Brønsted Acid Catalysis as a Tool for the Synthesis of Natural Products and Pharmaceuticals

Visible‐Light‐Driven Photochemical Activation of sp³ C−H Bond for Hemiaminal Formation

Organocatalysts for enantioselective synthesis of fine chemicals: definitions, trends and developments

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N‐Phosphinyl Phosphoramide—A Chiral Brønsted Acid Motif for the Direct Asymmetric N,O‐Acetalization of Aldehydes

Cited by 46 publications

References 45 publications

Enantioselective Brønsted Acid Catalysis as a Tool for the Synthesis of Natural Products and Pharmaceuticals

Enantioselective Brønsted Acid Catalysis as a Tool for the Synthesis of Natural Products and Pharmaceuticals

Visible‐Light‐Driven Photochemical Activation of sp3 C−H Bond for Hemiaminal Formation

Organocatalysts for enantioselective synthesis of fine chemicals: definitions, trends and developments

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Product

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Visible‐Light‐Driven Photochemical Activation of sp³ C−H Bond for Hemiaminal Formation