Browsing by Author "Liao, Jen-Yu"

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Multistep divergent synthesis of benzimidazole linked benzoxazole/benzothiazole via copper catalyzed domino annulation
(2013)
Liao, Jen-Yu
;
Selvaraju, Manikandan
;
Chen, Chih-Hau
;
Sun, Chung-Ming
;
應用化學系
An efficient, facile synthesis of structurally diverse benzimidazole integrated benzoxazole and benzothiazoles has been developed. In a multi-step synthetic sequence, 4-fluoro-3-nitrobenzoic acid was converted into benzimidazole bis-heterocycles, via the intermediacy of benzimidazole linked ortho-chloro amines. The amphiphilic reactivity of this intermediate was designed to achieve the title compounds by the reaction of various acid chlorides and isothiocyanates in a single step through the in situ formation of ortho-chloro anilides and thioureas under microwave irradiation. A versatile one pot domino annulation reaction was developed to involve the reaction of benzimidazole linked ortho-chloro amines with acid chlorides and isothiocyanates. The initial acylation and urea formation followed by copper catalyzed intramolecular C-O and C-S cross coupling reactions furnished the angularly oriented bis-heterocycles which bear a close resemblance to the streptomyces antibiotic UK-1.
Regioselective Synthesis of Angular Isocoumarinselenazoles: A Benzoselenazole-directed, Site-specific, Ruthenium-catalyzed C(sp(2))-H Activation
(2018-03-01)
Dhole, Sandip
;
Liao, Jen-Yu
;
Kumar, Sunil
;
Salunke, Deepak B.
;
Sun, Chung-Ming
The synthesis of new, angular isocoumarinselenazoles is described, which involves the construction of 2-amino benzoselenazoles and their regioselective C2N-alkylation and alkyne insertion. An expeditious and metal-free synthesis of 2-aminobenzoselenazoles by the reaction of methyl 3-amino-4-fluorobenzoate and isoselenocyanates was achieved. Further N-alkylation of the 2-aminobenzoselenazoles resulted the formation of two regioisomers with different reactivities towards the alkyne insertion. The regioselective construction of the a-pyrone ring on the benzo[1,3-d] selenazole skeleton was achieved via a ruthenium (II)-catalyzed oxidative annulation. It is clear that the selenazole nitrogen plays an important role in the observed selectivity.