Olefin synthesis by two-fold extrusion processes. Part II. Synthesis of some very hindered olefins

摘要: Reaction of hindered thiones with diazo-compounds affords Δ3-1,3,4-thiadiazolines, which by two-fold extrusion afford in good yield very olefins. In this way 2-diphenylmethylenebornane (VI), 2-diphenylmethylene-1,3,3-trimethylnorbornane (VIII), 1,1-di-t-butyl-2,2-diphenylethylene (XII), and 2-di-t-butylmethylenebornane have been prepared. The latter is probably the most olefin prepared to date. steric limitations approach explored. It was not possible obtain tetra-t-butylethylene (XIV) or 2-di-t-butylmethylene-1,3,3-trimethylnorbornane (XV).