(E)-3-[(S)-1-(5-Formyl-1,3-dimethyl-2,6-dioxo-1,2,3,6-tetrahydro-pyrimidin-4-yl)-pyrrolidin-2-yl]-acrylic acid ethyl ester                                                                                                                                                                                              以
                                                                                         xylene                                                                                  为溶剂,
                                                                                                                                                    反应 20.0h,
                                                                                                                以93%的产率得到(3aR,5S,12S)-12-ethoxycarbonyl-7,9-dimethyl-1,2,3,3a-tetrahydro-3a,5-ethanopyrrolo[4,5-b]pyrimido[4,5-d][1,3]oxazine-6,8(7H,9H)-dione