2,2-dimethyl-5-(2,2-pentamethylenetetrahydrooxazinylmethylene)-1,3-dioxane-4,6-dione                                                                                                                                                                                                                                                                              600.0 ℃
                                                                                                                            、1.33 Pa
                                                                                条件下,
                                                                                                                反应 0.25h,
                                                                                                                生成                                                 spiro[4,4a-dihydro-3H-pyrrolo[1,2-c][1,3]oxazine-1,1'-cyclohexane]-5-one   、                                                                                             4a-Hydroxyspiro[3,4-dihydropyrrolo[1,2-c][1,3]oxazine-1,1'-cyclohexane]-5-one