Synthesis of tetrasubstituted δ-lactones

Article abstract of DOI:10.1016/S0040-4039(97)10120-4

A versatile route for the synthesis of 6-lactones via oxidation of tetrasubstituted cyclopentanenes is described. Each step in the synthetic pathway from cis-2-oxabicyclo[3.3.0]oct-6-en-2one to the ketones proceeds with excellent regio- and stereoselectivity and in good yield. Baeyer-Villiger oxidation of the cyclopentanone 21 with a further methyl substituent at C-1' of the side chain gives a single δ-lactone 22 whereas a 3:1 mixture of regioisomers 12 and 13 is obtained from the analogue 11 with no substituent at C-1'.