Ring-Expansion of Thioacetal Ring via Bicyclosulfonium Ylide. Effect of Protic Nucleophile on Ylide Intermediate
作者:Takashi Mori、Yuichi Sawada、Akira Oku
DOI:10.1021/jo991775x
日期:2000.6.1
reaction of 2-(3-diazo-2-oxopropyl)-2-methyl-3-oxathiolane 9f in the absence of AcOH gave 4-oxa-7-thiocan-2-en-1-one 19 via a sulfonium ylide intermediate, whereas, in the presence of AcOH, an alternative regioisomer 20 was also formed competitively with 19 via an oxonium ylide intermediate.
2-(3-重氮-2-氧代丙烷-1-基)-2-甲基二硫杂环戊烷9a,2-(4-重氮-3-氧代丁烷-2-基)-2-甲基二硫杂环戊烷9c和2-(3 -重氮-2-氧代丙烷-1-基)-2-甲基-1,3-二硫杂环丁烷9b与Rh(2)(OAc)(4)得到三碳环扩环产物dithiocan-2-en-1-one分别参见图13a,13c和二硫南-2-烯-1-酮13b。2-(5-重氮-4-氧杂戊基)-2-甲基二硫杂环戊烷9e也给出了五碳环扩环产物二硫南-3-en-1-one 13e和5-亚甲基二硫烷-1-one 13'e。另一方面,2-(4-重氮-3-氧丁基)-2-甲基二硫杂环戊烷9d在AcOH的存在下反应,得到被乙酰氧基取代的四碳扩环产物16d。另外,在不存在AcOH的条件下,2-(3-重氮-2-氧丙基)-2-甲基-3-氧杂硫杂环戊烷9f的反应通过α-氨基苯甲酸产生4-氧杂-7-硫代硫烷-2-en-1-one