Stereocontrolled synthesis of naturally occurring polyacetylenes characterized by (E)-1-en-3-yne, (E)-1-ene-3,5-diyne, (1E,5E)-1,5-dien-3-yne, and (1E,7E)-1,7-diene-3,5-diyne moieties

A stereocontrolled synthesis of five naturally-occurring polyacetylenes, i.e. Me (E)-5-(2-thienyl)-2-penten-4-ynoate, (E)-N-methyl-N-(2-methylpropyl)-2-decen-4,6-diynamide, (E)-1-(3-methyl-2-butenoyloxy)-2-decen-4,6-diyne, (2E,6E)-1-acetoxy-2,6-decadien-4-yne (I) and (2E,8E)-1-acetoxy-2,8-decadien-4,6-diyne, is reported.  The flexible strategy involves Pd(O)-Cu(I)-catalyzed coupling reactions to construct the C skeleton of the target mols. and to prep. an important C5 building block, i.e. (E)-2-penten-4-yn-1-ol.  This compd. is also a useful intermediate to lipoxins A and B.  A highly diastereoselective Pd-catalyzed C-C bond-forming reaction has been used in a key synthetic step to I.