Intramolecular nucleophilic displacement of halogen by phosphinate and thiophosphinate anions: relative rates of formation of five- and six-membered rings 1
作者:Amirah Chaudhry、Martin J. P. Harger、Philippa Shuff、Alison Thompson
DOI:10.1039/a900623k
日期:——
Intramolecular nucleophilic substitution transforms the phosphinate anions XCH2CH2(CH2)nCH2(Ph)P(O)O– (n = 0, 1; X = Br, Cl) (Et3NH+ salts; CH2Cl2 solution) into cyclic phosphinate esters 14 (n = 0, 1); unusually the five-membered ring product (n = 0) is formed only 4.3 (X = Br) or 5.7 (X = Cl) times faster than the six (n = 1). The analogous cyclisation of the thiophosphinate anions ClCH2CH2(CH2)nCH2(Ph)P(S)O–
分子内亲核取代使次膦酸酯阴离子XCH 2 CH 2(CH 2)n CH 2(Ph)P(O)O –(n = 0,1; X = Br,Cl)(Et 3 NH +盐; CH 2 Cl 2溶液)成环次膦酸酯14(n = 0,1); 异常的五元环的产物(Ñ = 0)仅形成4.3(X =溴)或快于5.7(X = Cl)的倍六(Ñ = 1)。硫代次膦酸酯阴离子ClCH 2 CH 2(CH 2)的类似环化n CH 2(Ph)P(S)O –(n = 0,1)得到的产物16(n = 0,1)的环上有硫原子;现在,五元环的形成速度比六元环快30倍,但仍具有适度的速率优势。