A 1H and 13C NMR study of the reaction of a series of 2-alkyloxa- and 2-alkylthiazolines 3-Xaâc with 4,6-dinitrobenzofuroxan (DNBF) in DMSO revealed the formation of the C-bonded Ï-adducts 5-Xaâc. Product isolation following addition of Et3N or KOAc, afforded the Et3NH+ or K+ salts of the DNBF adducts, respectively. The NMR results showed conclusively that coupling of the DNBF moiety with the oxazoline or thiazoline heterocycle occurred at the α position of the 2-alkyl side-chain. A most reasonable mechanism for this coupling involves initial formation of a transient N-bonded adduct between the N-heterocycle and DNBF, which subsequently rearranges through the action of base to the C-bonded adduct as the product of thermodynamic control. The relevance of this work to oxa- and thiazoline-based proinsecticide is emphasized.
对一系列 2-烷氧基
噻唑和 2-烷基
噻唑 3-Xaâc 与 4,6-二硝基
苯并呋喃(DNBF)在
二甲基亚砜(
DMSO)中的反应进行的 1H 和 13C NMR 研究显示,形成了 C 键 Ï 加合物 5-Xaâc。加入 Et3N 或 KOAc 后进行产物分离,分别得到了 DNBF 加合物的 Et3NH+ 或 K+ 盐。核磁共振结果明确显示,DNBF 分子与
噁唑啉或
噻唑啉杂环的偶联发生在 2-烷基侧链的δ位。这种耦合的最合理机制是 N-杂环和 DNBF 之间最初形成瞬时 N 键加合物,随后在碱的作用下重新排列为 C 键加合物,成为热力学控制的产物。这项工作与氧杂和
噻唑啉类
杀虫剂的相关性得到了强调。