Medium-sized cyclophanes. 2. Bromination of 8-methoxy[2.2]metacyclophanes
                                
                                    
                                        作者:Takehiko Yamato、Seiji Ide、Kiwamu Tokuhisa、Masashi Tashiro                                    
                                    
                                        DOI:10.1021/jo00027a048
                                    
                                    
                                        日期:1992.1
                                    
                                    When 8-methoxy[2.2]metacyclophanes 5 are treated with benzyl trimethylammonium tribromide in dichloromethane, the transannular reaction products, tetrahydropyrene 6 and 7 are obtained along with 5-bromo-8-methoxy[2.2]metacyclophanes 8.  The bromination of 5-tert-butyl-8-methoxy[2.2]metacyclophanes 9a-9g in dichloromethane is carried out under the same conditions to afford tetrahydropyrene derivatives exclusively.  On the other hand, when the bromination reactions are performed in various alcohols, alkoxy-substituted tetrahydropyrenes 11 and 12 are obtained in good yields, which are easily dehydrogenated with DDQ to afford the corresponding pyrene derivatives.  The reaction mechanisms of the above reactions are also discussed.