The chemistry of fungi. Part 74. Synthesis of (±)-5-butyl-6,8-dihydroxy-3-pentyl-3,4-dihydroisocoumarin
Afzal, Sheikh M.; Pike, Richard; Rama, Nasim H.; Smith, Ian R.; Turner, Eric S.; Whalley, W. Basil
Журнал:
Journal of the Chemical Society, Perkin Transactions 1
Дата:
1978
Аннотация:
The title compound (1; R<sup>1</sup>= Bu<sup>n</sup>, R<sup>2</sup>= H), which corresponds to the (+)-dihydro-derivative of fusamarin (2), a metabolite of an unidentified species of Fusarium, has been synthesised. (2-Butyl-3,5-dimethoxyphenyl)acetic acid (3; R<sup>1</sup>= OH, R<sup>2</sup>= Bu<sup>n</sup>) was obtained from ethyl 3,5-dimethoxyphenylacetate by way of the corresponding 2-formyl derivative (3; R<sup>1</sup>= OEt, R<sup>2</sup>= CHO). Reaction of the acid chloride (3; R<sup>1</sup>= Cl, R<sup>2</sup>= Bu<sup>n</sup>) with pentylmagnesium bromide furnished 1-(2-butyl-3,5-dimethoxyphenyl)heptan-2-one (4; Ru = Bu<sup>n</sup>), which was reduced to the alcohol (5; R<sup>1</sup>= H, R<sup>2</sup>= Bu<sup>n</sup>). Formylation of the acetate (5; R<sup>1</sup>= Ac, R<sup>2</sup>= Bu<sup>n</sup>), followed by oxidation and hydrolysis of the ester residue, gave (±)-5-butyl-3-pentyl-6,8-dimethoxy-3,4-dihydroisocoumarin (1; R<sup>1</sup>= Bu<sup>n</sup>, R<sup>2</sup>= Me), which was demethylated to (1; R<sup>1</sup>= Bu<sup>n</sup>, R<sup>2</sup>= H). In model experiments (±)-6,8-dihydroxy-3-pentyl-3,4-dihydroisocoumarin (1; R<sup>1</sup>= R<sup>2</sup>= H) and related derivatives, together with associated isochromans of type (7), have been synthesised.
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