Acylation of oxindoles using methyl/phenyl esters <i>via</i> the mixed Claisen condensation – an access to 3-alkylideneoxindoles
作者:Ramdas Sreedharan、Purushothaman Rajeshwaran、Pradeep Kumar Reddy Panyam、Saurabh Yadav、C. M. Nagaraja、Thirumanavelan Gandhi
DOI:10.1039/d0ob00789g
日期:——
Predominantly, aggressive acid chlorides and stoichiometric coupling reagents are employed in the acylating process for synthesizing carbonyl tethered heterocycles. Herein, we report simple acyl sources, viz. methyl and phenyl esters, which acylate oxindoles via the mixed Claisen condensation. This straightforward protocol is mediated by LiHMDS and KOtBu and successfully applied to a wide range of
palladacycle‐catalyzed aromatic carbonylation reaction of arylformates with aryl iodides or bromides has been developed. Commercially available and easily prepared arylformates were employed as carbonyl sources without the use of externalcarbonmonoxide. The present catalytic system shows broad functional group tolerance and affords aryl benzoate derivatives in good to excellent yields.
N-Heterocyclic carbene catalysed aerobic oxidation of aromatic aldehydes to aryl esters using boronic acids
作者:Panjab Arde、B. T. Ramanjaneyulu、Virsinha Reddy、Apurv Saxena、R. Vijaya Anand
DOI:10.1039/c1ob06566a
日期:——
The organocatalytic behavior of N-heterocyclic carbenes in the aerobicoxidation of aromatic aldehydes to esters with boronic acids has been explored. This transition metal-free protocol allows access to a wide variety of aromatic esters in good to excellent yields under mild reaction conditions.
The first example of a palladium-catalyzed aerobic oxidative coupling of acyl chlorides with arylboronic acids has been developed, leading to a wide range of aryl benzoates in good to excellent yields. This catalytic system shows broad functional group tolerance. Preliminary mechanistic experiments using deuterium labeling showed that the oxygen atom was derived from dioxygen.
Direct Esterification of Aromatic Aldehydes with Tetraphenylphosphonium Bromide under Oxidative N-Heterocyclic Carbene Catalysis
作者:Bandaru T. Ramanjaneyulu、Manish Pareek、Virsinha Reddy、R. Vijaya Anand
DOI:10.1002/hlca.201300369
日期:2014.3
An unconventional reagent, tetraphenylphosphonium bromide, was employed as a phenyl source in the direct transformation of aromaticaldehydes to the corresponding phenyl esters under oxidative N‐heterocyclic carbene (NHC) catalysis. The phenyl esters were obtained in moderate yields under mild and organocatalytic conditions.