We have developed a metal-free approach for synthesizing E-trifluoromethylated alkenes from readily available aldehydes and the N-hydroxyphtalimide ester of trifluoropropionic acid. To address the challenge of defluorination, we conducted high-throughput screening of reaction conditions. We discovered that acid-base co-catalysis effectively suppresses defluorination, thereby enhancing product yields. A key advantage of our method is its reliance on inexpensive, commercially available starting materials and straightforward reaction conditions.