Synthesis of 9-Deoxycotylenol Derivatives and Their Seed Germination-Stimulating Activity

9-Deoxy-15-methoxymethoxycotylenol and 9-deoxy-19-methoxymethoxycotylenol were synthesized to clarify a role of the 9α-hydroxyl of cotylenol, a common aglycon of cotylenins possessing potent plant growth-regulating activities. Both of the 9-deoxycotylenol derivatives stimulated germination of lettuce seeds and therefore it has been clarified that the 9α-hydroxyl of cotylenol is not essential for the biological activities.