Synthesis of 1,6-Hexandiol, Polyurethane Monomer Derivatives via Isomerization Metathesis of Methyl Linolenate

Cross metatheses of tung oil, a nonedible vegetable oil and α-eleostearic acid ((9Z,11E,13E)-octadeca-9,11,13-trienoic acid, ESA) methyl ester (1), obtained from tung oil containing the same highly unsaturated, conjugated double bonds, have been carried out with cis-1,4-diacetoxy-2-butene (2) using Hoveyda-Grubbs (3-HG2) or Grubbs second or third generation catalysts (3-G2 or 3-G3). The reactions followed by Pd/C-catalyzed hydrogenation give methyl 11-acetoxyundecanoate (4) as a polyester raw material, 1,6-diacetoxy-hexane (5) as a precursor of 1,6-hexanediol (6) polyurethane monomer, and heptyl acetate as a fragrance (7) in 53–99% yields after Pd/C-catalyzed hydrogenation. The one-pot isomerization metathesis of α-linolenic acid ((9Z,12Z,15Z)-9,12,15-octadecatrienoic acid, ALA) methyl ester (7) using 2 as cross coupling agent, RuHCl(CO)(PPh3)3 (9) as isomerization, and 3-G2 as a metathesis catalyst followed by Pd/C catalyzed hydrogenation leads also to the formation of 5 and the homologues of 4 and 7 in ...