Ring-expansion reactions of Cyrene and derivatives with ethyl diazoacetate

Johannes Puschnig; Oscar Lamb; Christopher Sumby; Ben Greatrex

Just Accepted

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Ring-expansion reactions of Cyrene and derivatives with ethyl diazoacetate

Johannes Puschnig, Oscar Lamb, Christopher Sumby, Ben Greatrex

Abstract

The ring-expansion/homologation of the biomass derivative CyreneTM (6,8-dioxabicyclo[3.2.1]octan-4-one) has been developed via Lewis-acid promoted reactions with ethyl diazoacetate. Insertion into the C3-C4 bond gave a ring-expanded β-ketoester regioisomer as an equilibrating mixture of diastereomers, which was subjected to a one-pot hydrolysis and decarboxylation to give the 7,9-dioxabicyclo[4.2.1]nonan-5-one system (homocyrene). The reactivity of homocyrene was then investigated in a series of transformations known for the parent 6,8-dioxabicyclo[3.2.1]octan-4-one system, including the Baeyer-Villiger oxidation affording S-6-(hydroxymethyl)pyran-2-one which has been used for the synthesis of jasmine lactone, and another one-carbon ring expansion. The ring-expansion process for Cyrene could be used to prepare chiral C6 and C7 synthons on scale from biomass.

CH24163 Accepted 30 March 2025