Copper-catalyzed aerobic C-C bond cleavage of lactols with N-hydroxy phthalimide for synthesis of lactones

• Main Authors: Tnay, Ya Lin, Chiba, Shunsuke
• Other Authors: School of Physical and Mathematical Sciences
• Format: Article
• Language: English
• Published: 2015
• Subjects: DRNTU::Science::Chemistry::Physical chemistry::Catalysis
• Online Access: https://hdl.handle.net/10356/107166; http://hdl.handle.net/10220/25414
• Institution: Nanyang Technological University

The transformation of cyclic hemiacetals (lactols) into lactones has been achieved by Cu-catalyzed aerobic C[BOND]C bond cleavage in the presence of N-hydroxy phthalimide (NHPI). The present process is composed of a multistep sequence including a) formation of exo-cyclic enol ethers by dehydration; b) addition of phthalimide N-oxyl radical to the enol ethers followed by trapping of the resulting C-radicals with molecular oxygen to form peroxy radicals; c) reductive generation of oxy radicals and subsequent β-radical fragmentation to generate lactones.