First total synthesis of acetylenic alcohol 15-methyltricosa-2,4-diyne-1, 6-diol (strongylodiol-G) derived from marine sponge

The first total and efficient synthesis of a naturally occurring acetylenic alcohol 15-methyltricosa-2,4-diyne-1,6-diol (strongylodiol-G) derived from marine sponge involving nine steps has been described. 1-Bromo-9-methyloctadecane (5) and hex-6-tetrahydropyranyloxyhex-2,4-diyn-1-al (9) which were initially synthesised separately starting from 1,8-octanediol (1) and propargyl alcohol (6), respectively, have been used as the final intermediates to obtain the title compound. The key steps in the synthesis involved ionic liquid-mediated bromination of 1,8-octanediol (1), tetrahydropyranylation of 8-bromooctan-1-ol (2) using acidic ionic liquid [bmim]HSO4 and monotetrahydropyranylation of hex-2,4-yn-1,6-diol (7) using ultrasonic energy.