Lycopodium triterpenoids. The structures and partial syntheses of 16-oxoserratenediol, 16-oxo-21-episerratenediol, 16-oxodiepiser-ratenediol, 16-oxoserratriol, 16-oxo-21-episerratriol, and 16-oxolycoclavanol, .ALPHA.,.BETA.-unsaturated ketones of serratane group.