(E)-4-Oxonon-2-enoic acid 1a is a fatty acid, isolated from the mycelium of Streptomyces olevaceus. Owing to its significant activity against various Gram-positive and Gram-negative strains and particularly Staphylococcus aureus ATCC 11632; it is an attractive target for structure-activity relationship. We report herein a straightforward synthesis of (E)-4-Oxonon-2- enoic acid 1a and its analogues in a single step using Wittig reaction. The antibacterial and antifungal activity assay of 1a and its analogues 1b-1g is presented.