| —— | 
                                        (2R,5R)-1-aza-2-(tert-butyl)-5-methoxycarbonyl-6,8-dioxo-7-[1-hydroxy-1’-methylvinylidene]-3-oxabicyclo[3.3.0]octane | 
                                        1571712-99-6 | 
                                        C14H19NO6 | 
                                        297.308 | 
                                    
                                                                                                                                            
                                        | —— | 
                                        (2R,5R)-1-aza-2-(tert-butyl)-5-methoxycarbonyl-6,8-dioxo-7-[(Z)-1-hydroxy-1’-(bromomethyl)vinylidene]-3-oxabicyclo[3.3.0]octane | 
                                        1571713-06-8 | 
                                        C14H18BrNO6 | 
                                        376.204 | 
                                    
                                                                                                                                            
                                        | —— | 
                                        (2R,5R)-1-aza-2-(tert-butyl)-5-methoxycarbonyl-6,8-dioxo-7-[(Z)-1-hydroxy-1’-(diethylmethylphosphonate)allylidene]-3-oxabicyclo[3.3.0]octane, | 
                                        1571713-58-0 | 
                                        C18H28NO9P | 
                                        433.395 | 
                                    
                                                                                                                                            
                                        | —— | 
                                        (2R,5R)-1-aza-2-(tert-butyl)-5-methoxycarbonyl-3-oxa-6,8-dioxobicyclo[3.3.0]octane | 
                                        159970-77-1 | 
                                        C12H17NO5 | 
                                        255.271 |