Morris William J, Custar Daniel W, Scheidt Karl A
Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, USA.
Org Lett. 2005 Mar 17;7(6):1113-6. doi: 10.1021/ol050093v.
[reaction: see text] A scandium triflate catalyzed, diastereoselective cyclization between aldehydes and beta-hydroxy dioxinones has been discovered. This process capitalizes on the untapped nucleophilicity of the embedded enol ether within the dioxinone core. The bicyclic compounds from the resulting cyclization can be isolated, or alternatively, alkoxide nucleophiles can be directly added. This in situ addition fragments the dioxinone rings and delivers the 3-carboxy-substituted tetrahydropyran-4-ones in good yields with high levels of diastereoselectivity.
[反应：见正文] 已发现三氟甲磺酸钪催化的醛与β-羟基二氧杂环己二酮之间的非对映选择性环化反应。该过程利用了二氧杂环己二酮核心内嵌入的烯醇醚未开发的亲核性。由此产生的环化反应生成的双环化合物可以分离出来，或者，也可以直接加入醇盐亲核试剂。这种原位加成使二氧杂环己二酮环断裂，并以高非对映选择性和良好的产率得到3-羧基取代的四氢吡喃-4-酮。
