Oxidative Cyclization of Aryl Ynones with NaNO2 for the Divergent Synthesis of NO2‐Containing Spiro[5.5]trienones, Indenones and Thioflavones

Abstract

AbstractA K2S2O8‐promoted nitration/spirocyclization of biaryl ynones using inexpensive NaNO2 as nitro source has been described. This cascade reaction is triggered by nitration of alkyne and followed by 6‐exo‐trig spirocyclization, dearomatization, forming the NO2‐containing spiro[5.5]trienones in 63–85% yields. The present reaction also provides a practical method for the synthesis of nitrated indenones and thioflavones with 58–85% yields.magnified image