This monograph introduces the excellent application of olefin metathesis approah for total synthesis biologically potent 10-membered lactone derived natural products, such as (+)-Mueggelone (a novel inhibitor of fish development), Herbarumin-I (Which interacts with bovine-brain calmodulin and inhibited the activation of the calmodulin-dependent enzyme cAMP phosphodiesterase and should have physiological effects of agrochemical and medicinal interest), and Stagonolides (which were shown to be a nonhost-speci c but selective phytotoxin. Leaves of C. arvense were most sensitive and leaves of tomato and pepper (both Solanaceae) were less sensitive to stagonolide, and demonstrated to be a strong inhibitor of root growth in seedlings of C. arvense and some other Asteraceae species). Herbarumins & Stagonolides could be served as eco-friendly effective plant pathogens compared to environmentally restricted chemical herbicides. This monograph is unique in dealing with the synthetic protocols for above natural products utilizaing olefin metathesis including full experimental procedures, analytical data, complete referenece sections and most useful for all synthetic organic chemists.