A total synthesis of alternaric acid (1) has been achieved. Key reactions include the Julia olefination of tertiary aldehyde 4 and phenylsulfone 5, and novel one-pot construction of 3-acyl-4-hydroxy-5,6-dihydropyrone via Fries type rearrangement of O-enolacyl group of beta-keto-delta-valerolactone toward alpha-position of the delta-lactone. The absolute configuration of alternaric acid has been shown to be that illustrated in structure 1.
Total Synthesis and Stereochemistry of Alternaric Acid
摘要:
Determination of the stereochemistry and the total synthesis of alternaric acid 1 has been achieved. The stereostructure of 1 has been elucidated by stereoselective synthesis of four diastereoisomers of the C(9)-C(14) fragment 6, which had been obtained as a degradation product during structural studies. Key reactions of the total synthesis of 1 include the Julia olefination of tertiary aldehyde 6 and phenylsulfone 7 and novel one-pot construction of 3-acyl-4-hydroxy-5,6-dihydro-2-pyrone via Fries-type rearrangement of the O-enol acyl group of beta-keto-delta-valerolactone toward the a-position of the delta-lactone. The absolute configuration of alternaric acid has been shown to be that illustrated in structure 1. The modified Fries-type rearrangement method has also been extended to the synthesis of some other compounds containing a tricarbonylmethane structure.
A total synthesis of alternaric acid (1) has been achieved. Key reactions include the Julia olefination of tertiary aldehyde 4 and phenylsulfone 5, and novel one-pot construction of 3-acyl-4-hydroxy-5,6-dihydropyrone via Fries type rearrangement of O-enolacyl group of beta-keto-delta-valerolactone toward alpha-position of the delta-lactone. The absolute configuration of alternaric acid has been shown to be that illustrated in structure 1.
Total Synthesis and Stereochemistry of Alternaric Acid
Determination of the stereochemistry and the total synthesis of alternaric acid 1 has been achieved. The stereostructure of 1 has been elucidated by stereoselective synthesis of four diastereoisomers of the C(9)-C(14) fragment 6, which had been obtained as a degradation product during structural studies. Key reactions of the total synthesis of 1 include the Julia olefination of tertiary aldehyde 6 and phenylsulfone 7 and novel one-pot construction of 3-acyl-4-hydroxy-5,6-dihydro-2-pyrone via Fries-type rearrangement of the O-enol acyl group of beta-keto-delta-valerolactone toward the a-position of the delta-lactone. The absolute configuration of alternaric acid has been shown to be that illustrated in structure 1. The modified Fries-type rearrangement method has also been extended to the synthesis of some other compounds containing a tricarbonylmethane structure.