SYNTHESIS OF PIPECOLIC ACID DERIVATIVES VIA AZA–DIELS–ALDER REACTIONS OF THIO-SUBSTITUTED 1,3-BUTADIENES WITH IMINIUM SALTS
                                
                                    
                                        作者:Shang-Shing P. Chou、Chia-Cheng Hung                                    
                                    
                                        DOI:10.1081/scc-120013722
                                    
                                    
                                        日期:2002.1.1
                                    
                                    The titled compounds 1a-b were readily prepared by thermal desulfonylation of thio-substituted-3-sulfolenes 2a-b. The Aza-Diels-Alder reactions of 1a-b with iminium salts derived from alkyl or aryl amine hydrochlorides and ethyl glyoxalate gave the pipecolic acid derivatives 3-4 in good yields with complete control of regiochemistry.