The diastereoselective cyclization of 2a to 5a, which was employed in our novel synthesis of dl-griseofulvin (7a), was studied in detail. It was found that the use of the metallic bases resulted in excellent diastereoselectively, whereas organic bases are ineffective for diastereoselective cyclization. Consequently, diastereoselective cyclization of 2 to 5 was proposed to proceed through the intramolecular Michael reaction under chelation control.
详细研究了2a到5a的不对映选择性环化,该反应用于我们dl-
灰黄霉素(7a)的新合成。 研究发现,使用
金属碱会产生极佳的不对映选择性,而有机碱则对不对映选择性环化无效。 因此,建议通过螯合控制下的分子内迈克尔反应进行2到5的不对映选择性环化。