Reactions of arylacetylenic compounds with arenes in the presence of aluminum halides

Abstract

Conjugated arylacetylenic ketones and aldehydes, propargyl-type alcohols, and arylacetylenes reacted with arenes in the presence of AlBr 3 or AlCl 3 as catalyst to give substituted indenes. 3-Arylpropynoic acids under analogous conditions gave rise to 3,3-diarylindan-1-ones, while the corresponding methyl esters were converted into methyl 3,3-diarylprop-2-enoates. The key intermediates in the transformations of acetylenic ketones and aldehydes and propargyl-type alcohols into indene derivatives are resonance-stabilized propargyl-allenyl cations -C≡C-C + ↔ -C + =C=C which reacted with one of the resonance structures to give isomeric indenes, depending on the substituent nature.

Alkenylation of Arenes and Heteroarenes with Alkynes

“…Aluminum halogenide (AlX 3 , X = Cl, Br)-promoted transformations of acetylene carbonyl compounds 606 and propargyl alcohols 608 with arenes have been widely studied (Scheme ). − Coordination of AlX 3 at the carbonyl oxygen of substrates 606 activates the carbonyl carbon C1. This electrophilic center reacts with arenes leading to species 607 , which are transformed into propargyl cations 609 . ,, The latter may also be generated from the corresponding propargyl alcohols 608 . , Cations 609 have the allenyl mesomeric form 610 .…”

“… − Coordination of AlX 3 at the carbonyl oxygen of substrates 606 activates the carbonyl carbon C1. This electrophilic center reacts with arenes leading to species 607 , which are transformed into propargyl cations 609 . ,, The latter may also be generated from the corresponding propargyl alcohols 608 . , Cations 609 have the allenyl mesomeric form 610 . These two resonance species 609 and 610 have two different reactive, electrophilic carbon centers (C1 and C3, respectively) that in reactions with arenes give two different products, viz., alkyne 611 or allene 612 (Scheme ).…”

“…Intramolecular cyclization of 613 – 615 leads to isomeric indenes 616 – 619 . In this work, the influence of the electronic character of the substituents in mesomeric cations 609 and 610 on their consequent transformations was thoroughly analyzed. It was shown that electron-donating substituents Ar, Ar′, and R capable of delocalizing positive charge favored the activation of the neighboring electrophilic center (C1 in 609 and C3 in 610 ) that guides the reaction via paths a or b, respectively (Scheme ).…”

Ceria-modified hierarchical Hβ zeolite as a robust solid acid catalyst for alkenylation of p-xylene with phenylacetylene

“…The alkenylation of arenes with alkynes provides an environmentally friendly strategy for production of alkenyl aromatic with high efficiency and atom economy [3,4]. Homogeneous metal complex catalysts show prominent activity and selectivity for production of alkenyl aromatics [5][6][7][8][9][10]; however, these catalysts are expensive, have low recyclability as homogeneous catalysts, and feature difficulties in purification of the desired products. Hence, it would be desirable to develop a more clean and economical method.…”