We report an efficient method for the direct β-acylation of 2-ylideneoxindoles with acyl chlorides in the presence of base-catalyzed by organophosphanes. A variety of functionalized 2-ylideneoxindoles were prepared in moderate to good yields under metal-free and mild conditions via a tandem phospha-Michael/O-acylation/intramolecular cyclization/ rearrangement sequence. The mechanistic investigations revealed that the C-O bond cleavage on possible betaine intermediate is the key step for the installation of keto-functionality at β-position of 2-ylideneoxindoles in a highly stereospecific manner. The synthetic utility of this protocol could also be proven by scale-up reactions and synthetic transformations of the products.
This work describes the synthesis of compounds containing thiazolidine and propargylamidic motifs. Their preparation follows a synthetic route containing two multicomponent reactions. First, the Asinger four-component reaction is used to prepare 3-thiazolines and 3-oxazolines. Secondly, these heterocyclic imines are converted into propargylamides by a copper-catalyzed three-component reaction using acyl chlorides and terminal alkynes. The synthetic route is characterized by mild conditions and many functional groups are tolerated. The formation of an unexpected α-alkynoxyamide is also presented.
A series of acyl fluorides was synthesized at 100 mmol scale using phase transfer catalyzed halogen exchange between acyl chlorides and aqueous bifluoride solution. The convenient procedure consists of vigorous stirring of the biphasic mixture at rt, followed by extraction and distillation. Isolated acyl fluorides (usually 7 g to 20 g) display excellent purity, and can be transformed into sterically hindered amides and esters, when treated with lithium amide bases and alkoxides under mild conditions.
We report the development
of a multifunctional reagent for the direct conversion of pyridines to
Boc-protected 2-aminopyridines with exquisite site- and chemoselectivity. The
novel reagent was prepared on 200 gram-scale in a single step, reacts in the
title reaction under mild conditions without precautions towards air or
moisture, and is tolerant of nearly all common functionality. Experimental and <i>in-situ </i>spectroscopic<i> </i>monitoring techniques provide detailed insights
and unexpected findings for the unique reaction mechanism.
Continuous flow synthesis of diaryl ketones by coupling of aryl Grignard reagents with acyl chlorides under mild conditions in the ecofriendly solvent 2-methyltetrahydrofuran
