Polyketide Derivatives

Methyl 6-methylsalicylate is the trail pheromone of some ants, it is also found in carabid beetle, 6-methylsalicylaldehyde in the defensive secretion of a cerambycid beetle, and 6-methylsalicylic acid is made by some Pénicillium moulds. Orsellinic acid and 6-methylsalicylic acid are

4 ch3cooh

h3cach^ch2 ch2 oh a polyketide fold

CHq cooh ho' ^ oh orsellinic acid cooh ho' ^ oh orsellinic acid ch3 condense,

Figure 4.1 The condensation of four acetic acid units to give an intermediate polyketide which by further reaction gives an acetogenin. The polyketide is a formal intermediate, not always having a real existence

^ reduce to OH

CH3 condense dehydrate/W0 / O

VJL X 0H

enolize

HO"

a^cooh

6-methylsalicylic acid

Figure 4.2 Formation of the acetogenin 6-methylsalicylic acid oh3o CH,0

"OH

2-hydroxy-6-methyl-acetophenone ch3

2-acetoxy-6-methyl-acetophenone oh 0

¿&CH3 mellein 3,4-dihydro-8-hydroxy-3-methylisocoumarin

0 0

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