- Photocatalytic Reductive Radical-Polar Crossover for a Base-Free Corey–Seebach Reaction
-
A metal-free generation of carbanion nucleophiles is of prime importance in organic synthesis. Herein we report a photocatalytic approach to the Corey–Seebach reaction. The presented method operates under mild redox-neutral and base-free conditions giving the desired product with high functional group tolerance. The reaction is enabled by the combination of photo- and hydrogen atom transfer (HAT) catalysis. This catalytic merger allows a C?H to carbanion activation by the abstraction of a hydrogen atom followed by radical reduction. The generated nucleophilic intermediate is then capable of adding to carbonyl electrophiles. The obtained dithiane can be easily converted to the valuable α-hydroxy carbonyl in a subsequent step. The proposed reaction mechanism is supported by emission quenching, radical–radical homocoupling and deuterium labeling studies as well as by calculated redox-potentials and bond strengths.
- Crespi, Stefano,Donabauer, Karsten,K?nig, Burkhard,Murugesan, Kathiravan,Rozman, Ur?a
-
supporting information
p. 12945 - 12950
(2020/09/23)
-
- Preparation method for synthesis of phenolic ester through thiocarboxylic acid mediated visible light catalyzed phenol acylation reaction
-
The invention discloses a preparation method for synthesis of phenolic ester through a thiocarboxylic acid mediated visible light catalyzed phenol acylation reaction. Thiocarboxylic acid compounds andphenol compounds are subjected to a site specific reaction under certain conditions to produce phenolic ester compounds, wherein the certain conditions are as follows: under the conditions of normaltemperature, normal pressure and visible light, K2CO3 is used as an alkaline catalyst, terpyridyl ruthenium dichloride hexahydrate is used as a photosensitizer and acetonitrile is used as a reaction solvent. Synthesis of phenolic ester under catalysis of visible light is realized, thiocarboxylic acid is used as an acylation reagent, and the site specific phenol esterification reaction is realizedefficiently under mild conditions of normal temperature, normal pressure and visible light. The method has mild reaction conditions, large substrate functional group tolerance, high applicability andhigh yield, and an efficient, reliable and economical preparation method is provided for synthesis of phenolic ester.
- -
-
Paragraph 0079; 0080; 0100; 0101; 0102
(2018/07/30)
-
- Rational design, synthesis and structure-activity relationships of 4-alkoxy- and 4-acyloxy-phenylethylenethiosemicarbazone analogues as novel tyrosinase inhibitors
-
In continuing our program aimed to search for potent compounds as highly efficient tyrosinase inhibitors, here a series of novel 4-alkoxy- and 4-acyloxy-phenylethylenethiosemicarbazone analogues were designed, synthesized and their biological activities on mushroom tyrosinase were evaluated. Notably, most of compounds displayed remarkable tyrosinase inhibitory activities with IC50 value of lower than 1.0 μM. Furthermore, the structure-activity relationships (SARs) were discussed and the inhibition mechanism and the inhibitory kinetics of selected compounds 7k and 8d were also investigated. Taken together, these results suggested that such compounds could serve as the promising candidates for the treatment of tyrosinase-related disorders and further development of such compounds might be of great interest.
- You, Ao,Zhou, Jie,Song, Senchuan,Zhu, Guoxun,Song, Huacan,Yi, Wei
-
p. 924 - 931
(2015/03/04)
-
- Synthesis of two alnustone-like natural diarylheptanoids via 4+3 strategy
-
The first total synthesis of (4E,6E)-1,7-bis(3,4-dihydroxyphenyl)-hepta-4, 6-dien-3-one and an alternative synthesis of (4E,6E)-1,7-bis(4-hydroxyphenyl)- hepta-4,6-dien-3-one, two natural diarylheptanoids, mainly based on Claisen-Schmidt condensation were described. The crucial steps of the syntheses were the condensation of OH-protected 4-aryl-2-butanones with OH-protected 3-aryl-acrylaldehydes by the in situ enamination and then deprotection of OH groups to give the corresponding natural diarylheptanoids. Copyright Taylor & Francis Group, LLC.
- Burmaoglu, Serdar,Celik, Huelya,Goeiksu, Sueleyman,Maras, Ahmet,Altundas, Ramazan,Secen, Hasan
-
experimental part
p. 1549 - 1562
(2009/11/30)
-
