Selective oxymetalation of terminal alkynes via 6-endo cyclization: mechanistic investigation and application to the efficient synthesis of 4-substituted isocoumarins.

ABSTRACT: The cyclization of heteroatom-containing alkynes with π acidic metal salts is an attractive method to prepare heterocycles because the starting materials are readily available and the organometallic compounds are useful synthetic intermediates. A new organometallic species in the heterocyclization provides an opportunity to synthesize heterocycles that are difficult to obtain. Herein, we describe a novel cyclic oxymetalation of 2-alkynylbenzoate with indium or gallium salts that proceeds with an unusual regioselectivity to give isocoumarins bearing a carbon-metal bond at the 4-position. This new type of metalated isocoumarin provided 3-unsubstituted isocoumarins that have seldom been investigated despite their important pharmacological properties. Indium and gallium salts showed high perfo

SUBMITTER: Kita Y 

PROVIDER: S-EPMC6053900 | biostudies-literature | 2018 Jul

REPOSITORIES: biostudies-literature