Gomeric acid

Four new diterpenoid oxides have been obtained from Sideritis gomerae. They are gomeraldehyde (cnt-8,13-epoxylabdan-15-al) and gomeric acid (cnt-8,13-epoxylabdan-15-oic acid) and their 13-epimers. ent-Labda-13-en-8/8,15-diol was also isolated. 3/3-Hydroxymanoyl oxide and the 18-benzoyloxy-derivative have been obtained" from Palafoxia rosea. 

The species S. gomerae, from Canary Islands, yielded five ent-labdanes [56] the four new em-manoyloxides, gomeraldehyde (95), 13-epi-gomeraldehyde (87), gomeric acid (96), 13-epi-gomeric acid (88) and the known e t-8a,15-dihydroxy-labd-13(14)-ene (109) this last product had been isolated previously by Jefferies and Payne [57] from an Australian Beyera species. 

If this bridge dissociates to release a relatively weak acid, such as fully hydrated metal monomers [e.g.,Fe(H20)6, the proton induces dissociation, but is not catalytic because the proton remains in the inner co-ordination sphere of the monomer as an associated hydration water or hydroxyl ion. One molecule of water must enter the inner co-ordination sphere of the underbonded metal as it dissociates from the oli-gomer to complete the co-ordination sphere. A water molecule may subsequently... 

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