In organic synthesis, decarboxylation and C–H bond functionalization are two major processes. The direct C–H bond functionalization of cyclic ethers through decarboxylation using electronically diverse cinnamic acid derivatives in the presence of synthesized biogenic CuO nanocatalysts under mild conditions is developed. The spherical CuO nanocatalysts were prepared by a hydrothermal method without using any external mediators. This methodology exhibited a wide range of substrate scope with good yields of alkenylated products. In addition, the experimental observation showed that the reaction proceeded through a radical mechanism.