Photochemical reactivity of 6α-hydroxy-7-keto neoclerodane diterpenoids

The photochemical reactivity, in methanol at λ = 254 nm, of two 6α-hydroxy-7-keto neoclerodane, isoeriocephalin (1) and teucrolivin B (2) was evaluated. From the first compound, two new products were obtained: the 6β-hydroxy epimer (3) and the ɛ-lactone (4). The second one yielded exclusively the new spiro γ-lactone (5). The formation of these new products can be explained by the well-known radical mechanism Norrish type I.