Divergent synthesis of withasomnines via synthesis of 4-hydroxy-1H-pyrazoles and Claisen rearrangement of their 4-O-allylethers
                                
                                    
                                        作者:Hayato Ichikawa、Ryo Watanabe、Yuiko Fujino、Yoshihide Usami                                    
                                    
                                        DOI:10.1016/j.tetlet.2011.06.061
                                    
                                    
                                        日期:2011.8
                                    
                                    4-Hydroxypyrazoles were synthesized by the alkaline hydrolysis of the Baeyer-Villiger oxidation products of 4-formylpyrazoles. This new synthesis of 4-hydroxypyrazoles was applied to the divergent synthesis of withasomnine alkaloids in a unique strategy, for which the key steps included the regioselective Claisen rearrangement of their 4-O-allyl-4-hydroxy-1H-pyrazoles and a Suzuki coupling of 4-trifluoromethanesulfonyloxy-1H-pyrazoles and arylboronic acids. (C) 2011 Elsevier Ltd. All rights reserved.