Selectivities in ionic reductions of alcohols and ketones with triethylsilane/trifluoroacetic acid

Mayr, Herbert; Dogan, Barbara

doi:10.1016/s0040-4039(96)02484-7

Cited by 25 publications

(8 citation statements)

References 13 publications

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“…Indeed, the synthetic scheme grounded on the addition of a suitable aldehyde to a solution of commercially available 1,2,4-trimethoxybenzene ( 19 ), previously treated with n -BuLi, in THF. The obtained biaryl alcohols 20-R 1 (75%), 20-R 2 (83%), 20-R 3 , and 20-R 4 (78%) were reduced by a first addition of trifluoroacetic acid followed by triethylsilane in dichloromethane to afford the corresponding compounds 21-R 1 , 21-R 2 , 21-R 3 , and 21-R 4 with high yield. , Subsequently, as described below (Scheme ), each compound was subjected to an oxidation reaction that was improved with cerium ammonium nitrate (CAN) providing the quinones 22-R 1 (98%), 22-R 2 (70%), 22-R 3 (75%), and 22-R 4 (65%). Afterward, the final products ( 11 – 16 ) were synthesized by the respective condensation of the quinone ring of 22-R 1 , 22-R 2 , 22-R 3 , and 22-R 4 with hypotaurine using salcomine as catalyst.…”

Section: Resultssupporting

confidence: 70%

Thiazinoquinones as New Promising Multistage Schistosomicidal Compounds Impacting Schistosoma mansoni and Egg Viability

et al. 2019

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Schistosomiasis is the most significant neglected tropical parasitic disease caused by helminths in terms of morbidity and mortality caused by helminths. In this work, we present the antischistosomal activity against Schistosoma mansoni of a rationally selected small set of thiazinoquinone derivatives, some of which were previously found to be active against Plasmodium falciparum and others synthesized ad hoc. The effects on larvae, juvenile, and adult parasite viability as well as on egg production and development were investigated, resulting in the identification of new multistage antischistosomal hit compounds. The most promising compounds 6, 8, 13, and 14 with a LC 50 value on schistosomula from ∼5 to ∼15 μM also induced complete death of juvenile (28 days old) and adult worm pairs (7 weeks old) and a detrimental effect on egg production and development in vitro. Structure−activity relationships (SARs) were analyzed by means of computational studies leading to the hypothesis of a redox-based mechanism of action with a one-electron reduction bioactivation step and the subsequent formation of a toxic semiquinone species, similarly to what was previously observed for the antiplasmodial activity. Our results also evidenced that the selective toxicity against mammalian cells or parasites as well as specific developmental stages of a parasite can be addressed by varying the nature of the introduced substituents.

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Section: Resultssupporting

confidence: 70%

Thiazinoquinones as New Promising Multistage Schistosomicidal Compounds Impacting Schistosoma mansoni and Egg Viability

et al. 2019

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“…The conversion of oxygen-rich, biomass-derived feedstocks to alternatively functionalized chemicals has gained growing interest because of its potential as a renewable source of fuels and chemicals. − Numerous strategies have been developed to this end, including polyol dehydration, − deoxygenation, − and deoxydehydration. ,− Each of these methods effects C–O bond cleavage to produce valuable chemical feedstocks for further functionalization.…”

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confidence: 99%

Vanadium Pyridonate Catalysts: Isolation of Intermediates in the Reductive Coupling of Alcohols

Griffin

Schafer

2020

Inorg. Chem.

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The reductive coupling of alcohols using vanadium pyridonate catalysts is reported. This attractive approach for C(sp 3 )−C(sp 3 ) bond formation uses an oxophilic, earth-abundant metal for a catalytic deoxygenation reaction. Several pyridonate complexes of vanadium were synthesized, giving insight into the coordination chemistry of this understudied class of compounds. Isolated intermediates provide experimental mechanistic evidence that complements reported computational mechanistic proposals for the reductive coupling of alcohols. In contrast to previous mononuclear vanadium(V)/vanadium(III)/vanadium(IV) cycles, this pyridonate catalyst system is proposed to proceed by a vanadium(III)/vanadium(IV) cycle involving bimetallic intermediates.

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“…The reduction of alcohol 9a to furnish the desired bromide 10 proved to be the most challenging transformation in the entire synthesis. The original route used a silane reduction sequence (Et 3 SiH/CF 3 CO 2 H) and our first pilot campaign employed this method. However, a full equivalent of the triethylsilyl ether 11 is produced in this reaction, which cannot be separated from the desired product by distillation (Scheme 3).…”

Section: Resultsmentioning

confidence: 99%

Development of a Scalable Process for CI-1034, an Endothelin Antagonist

Jacks

Belmont

Briggs

et al. 2004

Org. Process Res. Dev.

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A concise, convergent multikilogram synthesis of CI-1034 (1), a potent endothelin receptor antagonist, is described. A 15-step preparation from commercially available o-vanillin and benzenesulfonyl chloride employs a remarkably robust Suzuki coupling between a boronic acid and an aromatic sulfonate ester as the key synthetic step. A scalable route capable of producing multikilogram quantities of CI-1034 with no chromatographic steps is described in this contribution. Improvements to the process included using a 4-fluorobenzenesulfonate ester as a suitable substitute for the triflate group in the Suzuki reaction and the use of MgCl 2 as a substitute for TiCl 4 in a Dieckmann condensation to provide the benzothiazine dioxide core.

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Selectivities in ionic reductions of alcohols and ketones with triethylsilane/trifluoroacetic acid

Cited by 25 publications

References 13 publications

Thiazinoquinones as New Promising Multistage Schistosomicidal Compounds Impacting Schistosoma mansoni and Egg Viability

Thiazinoquinones as New Promising Multistage Schistosomicidal Compounds Impacting Schistosoma mansoni and Egg Viability

Vanadium Pyridonate Catalysts: Isolation of Intermediates in the Reductive Coupling of Alcohols

Development of a Scalable Process for CI-1034, an Endothelin Antagonist

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