Journal
JOURNAL OF ORGANIC CHEMISTRY
Volume 83, Issue 12, Pages 6673-6680Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acs.joc.8b00923
Keywords
-
Categories
Funding
- University of Calabria
- University of Pisa
Ask authors/readers for more resources
The cycloisomerization of readily available 2-alkynylbenzoic acids 1 in ionic liquids (ILs) as recyclable reaction media has been studied under the catalytic action of CuCl2. With substrates bearing an aryl group on the triple bond, a mixture of (Z)-3-alkylideneisobenzofuran-1(3H)-ones (from 5-exo-dig cyclization) and 1H-isochromen-1-ones (from 6-endo-dig cyclization) was observed in 1-ethyl-3-methylimidazolium ethyl sulfate (EmimEtSO(4)), while the reaction turned out to be selective toward the formation of the isobenzofuranone only using N-ethyl-N-methylmorpholinium dicyanamide [Mor(1,2)N(CN)(2)] as the solvent. The 5-membered product was also obtained selectively when the substrate bearing a terminal triple bond was employed, either in EmimEtSO(4 )or [Mor(1,2)N(CN)(2)]. On the other hand, 2-alkynylbenzoic acids bearing an alkyl or an alkenyl group on the triple bond selectively led, in EmimEtSO(4), to 1H-isochromen-1-ones, while the formation of a regioisomeric mixture was observed in [Mor(1,2)N(CN)(2)] In any case, the solvent/catalyst system could be easily recycled after extraction of the product from the reaction mixture with diethyl ether. DFT calculations have been carried out to clarify the reaction outcome depending on reaction conditions, and the structures of two representative products, which are (Z)-3-benzylideneisobenzofuran-1(3H)-one and (Z)-3-(4-methylphenylmethylidene)isobenzofuran-1(3H)-one, have been confirmed by X-ray diffraction analysis.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available