ABSTRACT
Sandal wood seed oil (Santalum album, from the Indian subcontinent) is a rich source (70% of the total fatty acid content) of a conjugated trans-ene-acetylenic acid, 18:2 (9c,11t) (santalbic acid or xymenic acid). The conjugated enyne system offers great potential for the creation of novel and different fat molecules with functional groups, such as the allene. A chlorine-substituted furan fatty acid derivative can be obtained from methyl santalbate as follows: epoxidation of methyl santalbate (1) with m-chloroperoxybenzoic acid yields the corresponding trans-epoxy-acetylenic fatty ester derivative (2, yield 81%). Ring opening of the epoxy ring of compound 2 with lithium chloride affords methyl 11-chloro-12-hydroxy-9-octadecynoate (3) in high yield (89%). Chromic acid oxidation by the two-phase method of compound 3 furnishes methyl 11ch1oro-12-oxo-9-octadecynoate (4, 70%). The latter compound was isomerized with sodium hydrogencarbonate to give 12chloro-11-oxo-9,10-octadecadienoate (5, 75%). This unusual chloro-oxo-allenic C18 fatty ester derivative (5) was characterized by infrared spectroscopy (1942 cm-1, allenic str.); NMR spectroscopic analysis: δH 6.00 (9-H), 2.60 (13-H); δC 103.60(C-9), 208.24 (C-10), 106.44 (C-11), 193.91 (C-12). Treatment of compound 5 with bis(benzonitrile)palladium(II) chloride gives an exotic 3-chloro-furan fatty acid derivative [6, methyl 8-(4-chloro-5-hexyl-furan-2-yl)-octanoate] (Scheme 3) (Lie Ken Jie et al., unpublished data).
