| Abstract: | The mechanism of the cycloaddition reaction between ketene and allene to form methylene–cyclobutanones has been studied theoretically by HF /3–21G and MP2 /3–21G . These two reactions are believed to be unsynchronous and concerted, taking place through the twisted transition states. Four orbitals are mainly involved in each reaction, which is a “2 × 1 + 1]”-type cycloaddition. The activated barrier for the two reactions are 27.2 and 27.1 kcal/mol, respectively, at the level of MP 2/6–31G * based on the MP 2/3–21G geometries, i.e., these two reactions are compatible. © 1994 John Wiley & Sons, Inc. |
