Numerous macrolide antibiotics of bacterial or mould origin exhibit remarkable antimicrobial activities. The objectives of the project are: (a) to establish a general scheme leading to total syntheses of several representative macrolide antibiotics and (b) to develop new synthetic methodology required to execute vital tranformations. Six-Desoxyerthronolide (the common biosynthetic precursor leading to all the erythromycins presently known) and leucomycin-A5 (a representative member of 16-membered polyoxomacrolides) have been selected as target molecules for the current, first year of this project, and also efforts have been made to devise an efficient and mild method for the stereospecific synthesis of the beta-hydroxycarbonyl system, a basic unit present in the antibiotics. There has been made significant progress in achieving those two specific aims. Three paper already published and one in press all elaborate on the stereoselective synthesis of the beta-hydroxy-alpha-methylcarbonyl system using Z- and E- vinyloxyboranes. Syntheses of the above two metabolites have been virtually completed.