A high-yield robust LHMDS-mediated aldol-type reaction of benzyl maltol (2) and benzaldehyde (3) was developed using in situ IR to overcome the problems of low yield and yield fluctuation of the pilot synthesis. In situ IR studies indicated that unexpected side reactions of LHMDS and 3 reduced the yield of the aldol-type reaction. On the basis of the results, the reaction conditions were optimized.