L-proline's potential as an asymmetric catalyst in the HPESW reaction started a rush for its mechanistical behavior comprehension. Over thirty years, many proposals were done based on theoretical chemical concepts. Only with the advances on computational chemistry and better reaction conditions, L-proline's mechanism in HPESW reaction could be finally uncovered. The mechanistical comprehension of its role in the HPESW reaction lead to changes in organic chemistry that impact fifty years after its discovery. Based on this context, this brief review will make an approach of L-proline trajectory, from the HPESW reaction perspective, over fifth years.