(S)-(+)-1-Methylbutyl (E)-2-methyl-2-pentenoate, 1, and (S)-(+)-1-methylbutyl (E)-2,4-dimethyl-2-pentenoate 2, the aggregation pheromone for lesser grain borer Rhyzopertha dominica (F). were synthesized from crotylaldehyde in an overall yield of 30%. The chiral intermediate 6 was prepared in 90% enantiomer excess, employing the Sharpless asymmetric epoxidation. © 1990 Plenum Publishing Corporation.