Two hydrophenalenes (III; R = R″ = H, R′ = OMe; and R = H, R′ = Me, R″ = OMe) have been synthesised and shown to be identical with the cyclisation products of two unsaturated alcohols (I ; R = R″ = H, R′ = OMe; and R = H, R′ = Me, R″ = OMe). Some related reactions are described.