Enantiospecific Photochemical Norrish/Yang Type II Reaction of Nonbiaryl Atropchiral α-Oxoamides in Solution—Axial to Point Chirality Transfer

Ayitou, A. Jean‐Luc; Jesuraj, Josepha L.; Barooah, Nilotpal; Ugrinov, Angel; Sivaguru, Jayaraman

doi:10.1021/ja9050586

Cited by 77 publications

(36 citation statements)

References 16 publications

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“…Sivaguru and co-workers reported an atropselective Norrish/ Yang type-II reaction of atropisomeric α-oxoamides 460 in solution (Scheme 130). 285 The reaction proceeded from an nπ* excited state of the carbonyl compound that initiated γ-hydrogen abstraction from the N−Me substituent resulting in a 1,4-diradical. This diradical subsequently cyclized leading to chirally enriched β-lactam photoproduct 461.…”

Section: Atropselective Photoreactionsmentioning

confidence: 99%

Nonbiaryl and Heterobiaryl Atropisomers: Molecular Templates with Promise for Atropselective Chemical Transformations

et al. 2015

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Section: Atropselective Photoreactionsmentioning

confidence: 99%

Nonbiaryl and Heterobiaryl Atropisomers: Molecular Templates with Promise for Atropselective Chemical Transformations

et al. 2015

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“…Benzoyl formoyl chloride was synthesized by reaction of benzoyl formic acid and dichloromethyl methyl ether in dichloromethane using the previously reported procedure (Ayitou et al 2009). Similar to other failed attempts, a black mixture was obtained after a certain time.…”

Section: Unsuccessful Attemptsmentioning

confidence: 99%

Reactive dissolution of cellulose and pulp through acylation in pyridine

et al. 2012

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The direct acylation of cellulose and different pulps with various acid chlorides was systematically screened. The syntheses were started in a heterogeneous solid-liquid reaction medium in hot pyridine with aliphatic and aromatic acid chlorides. After a few hours, depending on the reagent used, a homogenous solution was obtained. The obtained cellulose esters usually show a high degree of substitution (DS) and polymerization and are soluble in organic solvents. Esterification of softwood dissolving pulp, hardwood kraft pulp and hardwood kraft pulp-hemicellulose poor were also studied. The results show that almost identical DS were obtained for pulp derivatives compared to esters of microcrystalline cellulose. Thermogravimetric analysis and differential scanning calorimetry of the synthesized materials showed an improved thermal stability and various discrete thermal transitions compared to the original cellulose. The scanning electron microscopy images of derivatives showed a relatively flat and smooth surface with an absence of fibrous structure. The reactive dissolution of cellulose or pulp in pyridine is a straightforward and easy route to obtain long-chain aliphatic and aromatic cellulose esters.

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“…In addition to phthalimide, succinimide and benzotriazole have been also used as the component for the N‐Mannich reaction ( 188 , 190 ). Reduction of the bases with NaBH 4 afforded the monomethylated products ( 189 , 191 ) . The intermediate 192 , which was prepared through an intramolecular N‐Mannich reaction, was reduced by Et 3 SiH to give the methylated product 193 .…”

Section: N‐methylationmentioning

confidence: 99%

Advances in the Synthesis of Methylated Products through Indirect Approaches

Chen

2019

Adv Synth Catal

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Methylation is a well‐known structural modification in organic and medicinal chemistry. In addition to using conventional methylation reagents for direct methylation, indirect methylation approaches have been also successfully applied, particularly to tackle the isolation difficulty among the methylated product, the unreacted starting material, and the dimethylated by‐product due to the structural similarities between them. This review summarizes recent advances in the synthesis of methylated products through indirect approaches – transforming functionalized intermediates into the methylated products. The indirect methodologies surveyed in this review are useful for chemists to select appropriate methylation strategies, particularly for the challenging synthesis of methylated products at a large scale in drug discovery. Abbreviations: AIBN: azobisisobutyronitrile; Cbz: carbobenzyloxy; DBU: 1,8‐diazabicyclo[5.4.0]undec‐7‐ene; DIBAL: diisobutylaluminium hydride; FA: formic acid; Fmoc: fluorenylmethyloxycarbonyl; KOTMS: potassium trimethylsilanolate; LAH: lithium aluminium hydride; LiHBEt3: lithium triethylborohydride; PC: photocatalyst; PMHS: polymethylhydrosiloxane; PSMS: zinc bis(phenylsulfonylmethanesulfinate); SAM: S‐adenosylmethionine; SET: single electron transfer; TBAF: tetra‐n‐butylammonium fluoride; TBS: tert‐butyldimethylsilyl; TEA: trimethylamine; TFA: trifluoroacetic acid; TMS: trimethylsilyl; Ts: 4‐toluenesulfonyl.

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Enantiospecific Photochemical Norrish/Yang Type II Reaction of Nonbiaryl Atropchiral α-Oxoamides in Solution—Axial to Point Chirality Transfer

Cited by 77 publications

References 16 publications

Nonbiaryl and Heterobiaryl Atropisomers: Molecular Templates with Promise for Atropselective Chemical Transformations

Nonbiaryl and Heterobiaryl Atropisomers: Molecular Templates with Promise for Atropselective Chemical Transformations

Reactive dissolution of cellulose and pulp through acylation in pyridine

Advances in the Synthesis of Methylated Products through Indirect Approaches

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