A Divergent Synthesis of Functionalized Unsaturated -Lactones from 详细信息    查看全文

• 作者：Jun Liu ; Mang Wang ; Bing Li ; Qun Liu ; Yulong Zhao
• 刊名：Journal of Organic Chemistry
• 出版年：2007
• 出版时间：June 8, 2007
• 年：2007
• 卷：72
• 期：12
• 页码：4401 - 4405
• 全文大小：111K
• 年卷期：v.72,no.12(June 8, 2007)
• ISSN：1520-6904

文摘

A divergent synthesis of functionalized unsaturated -lactones 2, 3, 4, and 5 has been developed startingfrom the readily available -alkenoyl--carboxyl ketene dithioacetals 1 in high to excellent yields undermild reaction conditions. Thus, 6-substituted 3-(1,3-dithiolan/dithian-2-ylidene)-3H-pyran-2(6H)-ones 2,obtained from a consecutive reduction with NaBH₄ and acidic workup of 1 via a novel vinylogousPummerer cyclization, can be further transformed into -pyranones 3, 4, and 5 upon a sequentialisomerization catalyzed by triethylamine (to give 3), followed by dethioacetalization (to give 4) or aformylation with Vilsmeier reagent (to give 5).