available five- and six-membered lactones and N-sulfonyllactams undergo efficient addition of t-butyl propiolate, and the resulting adducts undergo cycloisomerization to six- and seven-membered cyclic ethers or amines in the presence of pyridinium acetate. The ring expansion process occurs in generally good yields and is proposed to involve a nucleophilic catalysis mechanism.
容易获得的五元和六元内酯和N-磺酰内酰胺经过高效添加
丙酸叔丁酯,并且在
乙酸吡啶鎓存在下,所得的加合物进行环异构化为六元和七元环状醚或胺。环膨胀过程通常以良好的收率发生,并且被认为涉及亲核催化机理。