Oxidation of <i>cis</i>- and <i>trans</i>-3,5-Di-<i>tert</i>-butyl-3,5-diphenyl-1,2,4-trithiolanes:  Isolation and Properties of the 1-Oxides and the 1,2-Dioxides
                                
                                    
                                        作者:Hideaki Oshida、Akihiko Ishii、Juzo Nakayama                                    
                                    
                                        DOI:10.1021/jo0354591
                                    
                                    
                                        日期:2004.3.1
                                    
                                    Oxidation of trans-3,5-di-tert-butyl-3,5-diphenyl-1,2,4-trithiolane with dimethyldioxirane (DMD) or m-chloroperbenzoic acid MCPBA) gave two stereoisomeric (1S*,3S*,5S*)- and (1R*,3S*,5S*)1-oxides (16 and 17, respectively). Oxidation of 16 with DMD gave the (1S*,2R*,3S*,5S*)-1,2-dioxide (18) and the 1,1-dioxide 19, and that of 17 yielded the (1R*,2R*,3S*,5S*)-1,2-dioxide (20) mainly along with IS and 19. The structures of the 1,2-dioxides 18 and 20 were determined by X-ray crystallography. 1,2-Dioxides 18 and 20 isomerized to each other in solution, and the equilibrium constant K (20/18) is 19 in CDCl3 at 295 K. The kinetic study suggested a biradical mechanism for the isomerization. Isomerization of 16 and 17 to cis-3,5-di-tert-butyl-1,2,4-trithiolane I-oxides by treatment with Me3O+BF4- is also described.