Transition-metal-free intramolecular Friedel–Crafts reaction by alkene activation: A method for the synthesis of some novel xanthene derivatives

Abstract

In this work, new derivatives (substituted 9-methyl-9-arylxanthenes) of xanthene compounds (5a–l) of possible biological significance were synthesized by developing a new synthesis method. In order to obtain xanthene derivatives, the original alkene compounds to be used as the starting materials were synthesized in four steps using appropriate reactions. A cyclization reaction by intramolecular Friedel–Crafts alkylation was carried out in order to synthesize the desired xanthene derivatives using the alkenes as starting compounds. The intramolecular Friedel–Crafts reaction was catalyzed by trifluoroacetic acid (TFA) and provided some novel substituted 9-methyl-9-arylxanthenes with good yields at room temperature within 6–24 hours. As a result, an alkene compound was used for activation with TFA in the synthesis of xanthene through intramolecular Friedel–Crafts alkylation for the first time.

Development of ZnO/PANI/Ag nanocomposite for synthesis of bioactive xanthene‐1,8(2H)‐dione derivatives

“…Perlite NP@IL/ZrCl 4 Neat, 90 C 100 min 92% Moradi and Mirzaei [56] 8. TFA DCM 6 h 78% Yildiz et al [57] 9…”

“…Various synthetic routes were reported in the past for the development of xanthene by use of several catalyst such as Sc(OTf) 3 , [ 30 ] pTSA, [ 31 ] imidazolium hydrogen sulphate, [ 32 ] Y(NO 3 ) 3 ·6H 2 O [ 33 ] and SnCl 2 ·2H 2 O, [ 33 ] Fe 3 O 4 @Propylsilane@Histidine[HSO 4 − ] [ 34 ] and trifluoroacetic acid (TFA). [ 35 ] However, these methods have various shortcomings such as low product yield, use of toxic reagents, long reaction time, extensive work‐up and hazardous reaction conditions. Therefore, development of a simple heterogeneous catalyst is required for the catalytic synthesis of xanthene under green conditions to overcome these limitations.…”

“…À ] [34] and trifluoroacetic acid (TFA). [35] However, these methods have various shortcomings such as low product yield, use of toxic reagents, long reaction time, extensive work-up and hazardous reaction conditions. Therefore, development of a simple heterogeneous catalyst is required for the catalytic synthesis of xanthene under green conditions to overcome these limitations.…”

An efficient approach to access 2,5‐disubstituted 1,3,4‐oxadiazoles by oxidation of 2‐arenoxybenzaldehyde N‐acyl hydrazones with molecular iodine

“…To our ongoing efforts in the preparation of various heterocyclic pharmacological active motifs, [27][28][29] we herein synthesized new 2,5-disubstituted 1,3,4-oxadiazoles from their precursors N-acyl hydrazones with molecular iodine. However, to the best of our knowledge, molecular iodine-mediated oxidative cyclization for the synthesis of 2,5-disubstituted 1,3,4oxadiazole compounds from 2-arenoxybenzaldehydes and various substituted hydrazides has not yet been reported.…”

Synthesis of Novel 1,4-Diketone Derivatives and Their Further Cyclization

“…Here, it was developed an optimized procedure of the Stetter reaction using some ortho -(thio)­arenoxy benzaldehyde compounds ( 1a – 1n ) synthesized by us − and methyl vinyl ketone. We tried some NHC catalysts (Scheme ) in order to obtain a series of original ortho -(thio)­arenoxy-substituted 1,4-diketone compounds ( 2a – 2n ), and 3-benzyl-5-(2-hydroxyethyl)-4-methylthiazolium chloride ( 3b ) was found as the best NHC catalyst.…”