Henderson David A, Collier Philip N, Pavé Gregoire, Rzepa Paula, White Andrew J P, Burrows Jeremy N, Barrett Anthony G M
Department of Chemistry, Imperial College London, South Kensington, London SW7 2AZ, England.
J Org Chem. 2006 Mar 17;71(6):2434-44. doi: 10.1021/jo052637c.
Model studies on the synthesis of the tetracyclic ABCD ring system of lactonamycin (1) are described. The key step involved the double Michael addition reaction of alcohol 8 to propynoate esters to produce the BCD units 13 and 14 of the target 1. Alternatively, double Michael addition of alcohol 8 to di-tert-butyl acetylenedcarboxylate gave the corresponding BCD ring systems 36 and 37. Acid-mediated hydrolysis of the dihydroquinone monoketal units of 13 and 14 and 36 and 37 in the presence of air gave the corresponding quinones 7 and 39. These were converted into the tetracyclic ABCD units 6, 26a, 40, and 42 of lactonamycin (1) by either dihydroxylation or epoxidation and acid-catalyzed lactonization.
本文描述了关于内酯霉素（1）四环ABCD环系合成的模型研究。关键步骤涉及醇8与炔丙酸酯的双迈克尔加成反应，以生成目标化合物1的BCD单元13和14。另外，醇8与二叔丁基乙炔二羧酸酯的双迈克尔加成反应得到相应的BCD环系36和37。在空气中，13、14、36和37的二氢醌单缩酮单元经酸介导水解得到相应的醌7和39。通过双羟基化或环氧化以及酸催化内酯化反应，将这些醌转化为内酯霉素（1）的四环ABCD单元6、26a、40和42。
