Synthetic studies of kinamycin antibiotics: Stereoselective synthesis of the highly oxygenated D-ring and construction of the ABD-ring system of kinamycins

Abstract

A concise and stereoselective synthesis of the highly oxygenated D-ring of the kinamycin family of antitumor antibiotics was achieved from commercially available 3-methyl-2-cyclohexen-1-one. The key steps included a regioselective isomerization of a cis-epoxy alcohol, a regioselective reductive ring opening of a benzylidene ketal, and a stereoselective α-hydroxy-directed ketone reduction. The Ullmann coupling between a bromonaphthaldehyde AB-ring fragment and an α-iodocyclohexenone, which is a versatile D-ring precursor, effected the construction of the functionalized ABD-ring system that may provide access to kinamycin F and its structural analogues. A concise and stereoselective synthesis of the highly oxygenated D-ring of the kinamycins was achieved from commercially available 3-methyl-2-cyclohexenone. Also, a metal-catalyzed coupling reaction between an AB-ring fragment and a D-ring precursor enabled the construction of the functionalized ABD-ring system that may provide entry to synthesis of the kinamycins. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.