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Total Synthesis of (−)-Preussochromone D

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journal contribution
posted on 2019-05-28, 12:35 authored by Eric Kerste, Klaus Harms, Ulrich Koert
An efficient, stereoselective synthesis of the natural product (−)-preussochromone D is reported. The tricyclic skeleton was assembled by a diastereoselective intramolecular aldol addition of a chromanone to an α-ketoester. Further key steps are an asymmetric 1,4-addition of diisopropenyl zinc to a chromenone and an intermolecular diastereoselective aldol addition of methyl diazoacetate to an aldehyde. The diazo group was oxidized to generate the α-ketoester while oxidative side reactions at the chromanone could be prevented by the use of a difluoromethyl ether as a protecting group.