A Synthesis of Densely Functionalized 2,3-Dihydropyrans Using Ring-Closing Metathesis and Base-Induced Rearrangements of Dihydropyran Oxides
                                
                                    
                                        作者:Bernd Schmidt、Holger Wildemann                                    
                                    
                                        DOI:10.1002/1099-0690(200009)2000:18<3145::aid-ejoc3145>3.0.co;2-b
                                    
                                    
                                        日期:2000.9
                                    
                                    presence of lithium dialkylamides to functionalized 2,3-dihydropyrans or 2,3-dihydrofurans, respectively, is described. The regiochemical outcome of the reaction can be influenced by the relative configuration of the starting epoxides and the steric demand of the base. The 2,3-dihydropyrans obtained were converted stereoselectively to difunctionalized 3,4-dihydropyrans by the carbon-Ferrier reaction, or to
                                    描述了二氢
吡喃和二氢
呋喃氧化物的制备以及它们在二烷基
氨基
锂存在下的重排分别为官能化的 
2,3-二氢吡喃或 
2,3-二氢呋喃。反应的区域
化学结果会受到起始
环氧化物的相对构型和碱的空间需求的影响。获得的 
2,3-二氢吡喃通过碳-费里耶反应立体选择性地转化为双官能化的 
3,4-二氢吡喃,或通过添加
二甲酮(由
硝酸铈铵介导)转化为稠合的
缩醛。立体
化学结果通过机械建议合理化。