1. Metal-free and benign approach for the synthesis of dihydro-5′H-spiro[benzo[c]chromene-8,4′-oxazole]-5′,6(7H)-dione scaffolds as masked amino acids
- Author
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Behnaz Shafiee, Jackson O. Lay, Rohana Liyanage, Hadi Amiri Rudbari, Rudy Timm, M. Hassan Beyzavi, Joseph Duffield, and Ahmad Reza Khosropour
- Subjects
chemistry.chemical_classification ,010405 organic chemistry ,Chemistry ,Decarboxylation ,010402 general chemistry ,01 natural sciences ,Pollution ,Medicinal chemistry ,0104 chemical sciences ,Amino acid ,Solvent ,chemistry.chemical_compound ,Cascade reaction ,Atom economy ,Propylene carbonate ,Michael reaction ,Environmental Chemistry ,Oxazole - Abstract
An eco-friendly, straightforward, and three-component condensation/cascade reaction of 4-hydroxycoumarins and (Z)-azlactones to construct diversified dihydro-5′H-spiro[benzo[c]chromene-8,4′-oxazole]-5′,6(7H)-diones as new masked amino acid derivatives has been developed with high to excellent yields and regio- and diastereoselectivity. This metal-free reaction proceeds via a one-pot cascade Michael addition/lactonization/decarboxylation reaction utilizing reusable propylene carbonate as a green solvent. The scale-up examination was also performed, showing high atom economy under the reaction conditions. Moreover, the mechanism of the reaction was further investigated using isotope-labeling, LC-MS monitoring, and TLC-MALDI-MS.
- Published
- 2019