SYNTHESIS OF SOME BIOACTIVE ACETYLENIC ALCOHOLS, COMPONENTS OF THE MARINE SPONGE CRIBROCHALINA-VASCULUM

Grignard coupling of isopropylmagnesium bromide with 4-(tetrahydropyra nyloxy)bromobutane (2) and subsequent bromination gave 4. Alkylation o f 1-(tetrahydropyranyloxy)undec-10-yne (5) with 4 and 1-bromohexane, a cidic hydrolysis, and bromination furnished 7 and 9, respectively. Lik ewise, coupling of isobutylmagnesium bromide with 12-(tetrahydropyrany loxy)bromododecane (12) followed by bromination afforded 14. Alkylatio n of 1-(tetrahydropyranyloxy)-2-propyne (15) with 7, 9, and 14 and oxi dation of the respective products afforded the alkynals 16a-c. These o n reaction with lithium acetylide and subsequent chemoselective trans reduction of the internal alkynes led to the target compounds I-III.