Thymol Bromination – A Comparison between Enzymatic and Chemical Catalysis

Abstract

An efficient three‐component reaction involving carbon monoxide with a range of aryl bromides and N‐substituted acetoacetamides is reported for the synthesis of β‐keto amides. This transformation is promoted by Pd‐catalysis followed by an acid‐mediated deacetylation upon work‐up, enabling a large number of β‐keto amides to be isolated. Finally, d2‐13C‐dyclonine could be synthesized in three steps utilizing the developed catalytic system as the key step.

Synthesis, Characterization, Reactivity, Catalytic Activity, and Antiamoebic Activity of Vanadium(V) Complexes of ICL670 (Deferasirox) and a Related Ligand

“…The other complexes tested under the optimized reaction conditions showed almost the same conversion and selectivity (Table 10). A blank reaction without catalyst under the same conditions (as in [42] These results suggest that the complexes are intact during the catalytic cycle; therefore, the conversion of thymol is enhanced and the selectivity of the products is altered. The catalytic abilities of these complexes compare well with that of the vanadium complex [V V O(OMe)(MeOH)(L)] {H 2 L = 6,6′-[2-(pyridine-2-yl)ethylazanediyl]bis(methylene)bis(2,4-ditert-butylphenol); the optimized reaction conditions were: substrate/H 2 O 2 /KBr/HClO 4 1:2:2:2 for 0.010 mol of thymol}, for which 99 % conversion was obtained with 57 % selectivity towards 2,4-dibromothymol, 37 % towards 4-bromothymol, and the rest towards 2-bromothymol.…”

“…The identities of the obtained products were confirmed by GC-MS and 1 H NMR spectroscopy after their separation and by comparison with literature data. [42,43] Scheme 2. Products of the oxidative bromination of thymol (2-Brth = 2-bromothymol, 4-Brth = 4-bromothymol, 2,4-dBrth = 2,4-dibromothymol).…”

4,6‐Diacetyl Resorcinol Based Vanadium(V) Complexes: Reactivity and Catalytic Applications

“…Oxidative Bromination of Thymol: The oxidative bromination of thymol was carried out in the presence of KBr, 70 % aqueous HClO 4 , and 30 % aqueous H 2 O 2 in aqueous medium (Scheme ). The catalytic reaction led to the formation of three products, namely, 2‐bromothymol, 4‐bromothymol, and 2,4‐dibromothymol . Among these products 2,4‐dibromothymol is formed due to further bromination of monobrominated products.…”

Formate Oxidase (FOx) from Aspergillus oryzae: One Catalyst Enables Diverse H2O2‐Dependent Biocatalytic Oxidation Reactions

“…Enzymes, however, are also prone to oxidative inactivation by H 2 O 2 which is why a broad range of in situ H 2 O 2 generation methods have been investigated in recent years (Table S2 compares some established systems with respect to efficiency and waste generation). The goal is to provide the production enzymes with H 2 O 2 at rates that allow high catalytic turnover while minimising the undesired oxidative inactivation by excess H 2 O 2 . Today, glucose oxidase (GOx) is the catalyst of choice for in situ H 2 O 2 generation .…”