Substituent-Controlled Electrocyclization of 2,4-Dienones: Synthesis of 2,3,6-Trisubstituted 2H-Pyran-5-carboxylates and Their Transformations

[摘要]：A facile access to 2,3,6-trisubstituted 2H-pyran-5-carboxylates is developed by employing 2-alkyl-2-enals as reactants with acetoacetates. The reaction involves Knoevenagel condensation followed by a 6 pi-electrocyclization, in which the presence of the C2 alkyl substituent in the enals favors the formation of (E)-Knoevenagel adducts for the ensuing electrocyclization. The resulting 2H-pyrans are hydrogenated to form 3,4-dihydro-2H-pyrans and converted into the endoperoxides by singlet-oxygen cycloaddition.

[全文传递流程]：

一般上传文献全文的时限在1个工作日内