Alkyne-Mediated Approach to the Synthesis of (4R,5R)-5-Hydroxy-4- decanolide and (¢)-Muricatacin

Introduction. – Chiral 5-hydroxy-g-butyrolactones constitute an important class of natural products and have received considerable attention due to their interesting wide range of biological activities [1]. These compounds have found applications as insect anti-feedants [2], cytotoxic agents [3], and flavor constituents in wine, sherry, and tobacco smoke [4]. They also serve as important precursors for the synthesis of bioactive natural products [5] and other compounds, such as HIV-1 protease inhibitors [6]. (4R,5R)-5-Hydroxy-4-decanolide (1a ; Fig.) is one such g-butyrolactone which was recently found in male Nasonia vitripennis as an additional pheromone compound differing only in its configuration from the previously described (4R,5S)-5-hydroxy-4decanolide (1b) [7]. The enantiomers of these two compounds, (4S,5S)and (4S,5R)isomers 1c and 1d, were also natural compounds, named as L-factors, isolated from the cultures of Streptomyces griseus, which reveal autoregulatory properties [8]. Due to their notable bioactivity, the synthesis of L-factors has received attention of organic chemists and accordingly various strategies have been developed [9]. In few cases, (4R,5R)and (4R,5S)-isomers were also synthesized [10]. In continuation of our interest in the synthesis of bioactive lactones using alkyne-assisted approaches [11], Helvetica Chimica Acta – Vol. 98 (2015) 967