6-Methylenebicyclo[3.2.1]oct-1-en-3-one,atwisted and highly reactive enone,w as prepared for the first time by elimination of its bromide precursor.I ts reactions as ad ienophile with several dienes in Diels-Alder reactions proceeded smoothly to provide tricyclic and tetracyclic adducts,w hich allowed short syntheses (10-11 steps) of four kurane diterpenoids including 11b-hydroxy-16-kaurene,1 1 a-hydroxy-16kaurene,liangshanin G, and gesneroidin B. Figure 2. Formationa nd reaction of some bridgehead enones.