3-(1,3,5-Trioxo-7,11-diphenyl-2,4-diaza-spiro[5.5]undec-8-en-9-ylsulfanyl)-propionic acid                                                                                                                                                              在
                                                                                                                                                                                 phosphorus pentoxide                                                                                                                                  作用下,
                                                                                                                以
                                                                                         
苯                                                                                  为溶剂,
                                                                                                                                                    反应 12.0h,
                                                                                                                以62%的产率得到5',7'-diphenyl-2',3',7',8'-tetrahydro-2H,4'H,5'H-spiro[pyrimidine-5,6'-thiochromene]-2,4,4',6(1H,3H)-tetraone