Two synthetic routes to bicyclobutylidene are described. Bicyclobutylidene can be readily epoxidized to Q-oxadispiro [3.0. 3. l] nonane, and adds methylene to give dispiro [3.0. 3. l] nonane and dibromocarbene to give the corresponding Q,% dibromide. Reaction of the dibromide with methyllithium generated 1, 3-bis (trimethylene) propa-diene. This allene also reacted with dibromocarbene to give the mono-and bis adducts. Treatment of the ...