26933-59-5Relevant academic research and scientific papers
Pd-free Sonogashira coupling: One pot synthesis of phthalide via domino Sonogashira coupling and 5-exo-dig cyclization
Dhara, Shubhendu,Singha, Raju,Ghosh, Munmun,Ahmed, Atiur,Nuree, Yasin,Das, Anuvab,Ray, Jayanta K.
, p. 42604 - 42607 (2015/02/19)
Phthalides have been synthesized exclusively in one pot via Pd-free Sonogashira coupling. A Cu-catalyzed domino Sonogashira coupling and 5-exo-dig cyclization between suitable substituted ortho-bromobenzoic acids and terminal alkynes afforded phthalides in good yields under mild reaction conditions.
Tandem palladium/charcoal-copper(I) iodide (Pd/C-CuI) catalyzed Sonogashira coupling and intramolecular cyclization from 2-bromonicotinic acid (=2-bromopyridine-3-carboxylic acid) and ethynylarenes to 4-azaphthalides (=furo[3,4-b]pyridin-5(7H)-ones) and 5-azaisocoumarins (=5H-pyrano[4,3-b] pyridin-5-ones)
Begouin, Agathe,Queiroz, Maria-Joaor P.
experimental part, p. 1792 - 1801 (2011/12/02)
Several 4-azaphthalides (=furo[3,4-b]pyridin-5(7H)-ones) and 5-azaisocoumarins (=5H-pyrano[4,3-b]pyridin-5-ones) were prepared through a tandem heterogeneous Pd/C-mediated Sonogashira coupling and a 5-exo-dig or 6-endo-dig intramolecular cyclization of 2-bromonicotinic acid (=2-bromopyridine-3-carboxyclic acid) with various ethynylarenes or 3-ethynylthiophene. In the presence of Pd/C-Ph3P-CuI and Et 3N in dry dioxane under Ar at 90°, a mixture of 4-azaphthalides (usually the major product) and 5-azaisocoumarins was obtained after 3.5 h under normal heating (Schemes 3 and 4; Tables 1 and 2). This mixture of compounds was also obtained with the same catalytic system under microwave (MW) irradiation in only 25 min (Tables 3 and 4). The 1-ethynyl-3-methoxybenzene gave on heating only the corresponding 4-azaphthalide (Table 2), while under MW irradiation, both the 5-exo-dig and the 6-endo-dig products were obtained (Table 4). For the 3-ethynylthiophene, the regioselectivity for the corresponding 4-azaphthalide was achieved with both methods (Tables 2 and 4). Although the yields and the regioselectivity of the reaction generally remained the same with both methods, the use of MW allowed us to obtain the corresponding products in a shorter reaction time. From 4-ethynyl-N,N-dimethylaniline (=4-ethynyl-N,N- dimethylbenzenamine), the corresponding 4-azaphthalide and 5-isocoumarin were only obtained under MW irradiation (Tables 2 and 4). To the best of our knowledge, it is the first time that this kind of tandem reaction was applied to a pyridine derivative giving the corresponding 4-azaphthalides and 5-azaisocoumarins which are easily separated and may both show biological activity. Copyright
NHC-catalyzed oxidative cyclization reactions of 2-alkynylbenzaldehydes under aerobic conditions: Synthesis of O-Heterocycles
Park, Jong Hyub,Bhilare, Sachin V.,Youn, So Won
supporting information; experimental part, p. 2228 - 2231 (2011/07/09)
Chemical equations presented. An NHC-catalyzed, regio- and stereoselective oxidative cyclization of o-alkynylbenzaldehydes bearing an unactivated alkyne moiety as an internal electrophile has been developed to afford phthalides and isocoumarins. A single organocatalytic system enabled two sequential C-O bond formations to take place in an atom economical manner via highly efficient dual activation. Molecular oxygen in air could be utilized as a source of an oxygen atom for the oxidation of aldehydes to the corresponding benzoic acids under our newly developed reagent system.
One-pot synthesis of phthalides via regioselective intramolecular cyclization from ortho-alkynylbenzaldehydes
Li, Jim,Chin, Elbert,Lui, Alfred S.,Chen, Lijing
scheme or table, p. 5937 - 5939 (2010/11/21)
A one-pot synthesis of phthalides via an intramolecular 5-exo-dig cyclization of ortho-alkynylbenzaldehydes under mild NaClO2 oxidation conditions is described.
EFFECTIVE SYNTHESIS OF 7-BENZYLIDENEFUROPYRIDIN-5-ONE
Nishiwaki, Nagatoshi,Komatsu, Mitsuo,Ohshiro, Yoshiki
, p. 1013 - 1016 (2007/10/02)
The tittle compound was synthesized by silica gel assisted cyclization of 2-phenylethynylpyridine-3-carboxylic acid (3).It was also synthesized from 3-cyano-2-phenylethynylpyridine (6) in good yield by basic cyclization and dehydration processes.
