Puschnig, J.Lamb, O.Sumby, C.J.Greatrex, B.W.Polyzos, A.2025-09-152025-09-152025Australian Journal of Chemistry, 2025; 78(5):CH24163-1-CH24163-50004-94251445-0038https://hdl.handle.net/2440/147324The ring expansion and homologation of the biomass derivative Cyrene (6,8-dioxabicyclo[3.2.1]octan-4-one) has been developed by 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.en© 2025 The Author(s) (or their employer(s)). Published by CSIRO Publishing. This is an open access article distributed under the Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC)carbene; cyrene; diazo compounds; Jasmine lactone; levoglucosenone; organic green chemistry; ring expansion; valerolactoneJournal article10.1071/CH24163739825Sumby, C.J. [0000-0002-9713-9599]