Synthesis of Coumarins, 4-Hydroxycoumarins, and 4-Hydroxyquinolinones by Tellurium-Triggered Cyclizations1

~0%

~78%

~92%

~%

~%

~%

~53%

~%

~%

~%

~90%

~%

~%

~%

~9%

~%

~%

~%