Synthesis of neoflavenes by ligand coupling reactions with aryllead triacetates

The reaction of 4-methoxycarbonylchroman-3-one with aryllead triacetates gave the 4-aryl derivatives after 3-4 h reaction times in moderate to good yields. Unexpectedly, 2,4-diarylated derivatives were also obtained after longer reaction times. The activating methyl ester group proved difficult to remove by standard decarboxylation procedures. 4-Benzyloxycarbonylchroman-3-ones were therefore prepared and reacted with aryllead triacetates to afford the corresponding 4-aryl derivatives. These were subsequently decarboxylated, reduced and dehydrated to afford neoflavenes in modest overall yields. (C) 2000 Elsevier Science Ltd. All rights reserved.