Calyculin synthetic studies. Stereoselective construction of the C(14)-C(25) spiroketal subunit
                                
                                    
                                        作者:Amos B. Smith、James J.-W. Duan、Kenneth G. Hull、Brian A. Salvatore                                    
                                    
                                        DOI:10.1016/s0040-4039(00)93479-8
                                    
                                    
                                        日期:1991.9
                                    
                                    A convergent, stereocontrolled synthesis of the spiroketal fragment of calyculins A-H has been achieved.  Key transformations include the novel iodine monobromide-induced iodocarbonate cyclization of (+)-19, efficient coupling of epoxide (+)-14 with the sterically hindered dithiane 15, and a multi-step, one-pot conversion of open-chain precursor (-)-13 to spiroketal (+)-11.