Chemistry of Anti-HIV Active Trimeric Benzochromene Conocurvone: Synthetic Studies towards Monomeric Teretifolione B and Related Compounds

Pyranonaphthoquinone natural products are widely distributed in plants and microorganisms, and they have diverse biological activities. Angular benzochromenes are a small class of natural products isolated from Conospermum and Pentas plants. Conocurvone, a trimeric benzochromene isolated from Conospermum plants, has potent anti-HIV activity. We have focused compounds which exhibit biological activity, or in which the activity is further enhanced by having oligomeric structure as a target of total synthesis. In this paper, the discovery and biological activity of trimeric benzochromene conocurvone and its related compounds were outlined and synthetic studies toward monomeric chromenoquinones was described including our research, in which the benzochromene framework was constructed by Diels-Alder reaction of oxygenated furans and chromene-derived benzynes.