Intramolecular Friedel−Crafts-Type Reactions Involving <i>N</i>-Acyliminium Ions Derived from Glycine Templates
作者:Juan Domingo Sánchez、María Teresa Ramos、Carmen Avendaño
DOI:10.1021/jo010166y
日期:2001.8.1
Enantiomerically pure 4-substituted 2-aralkyl-2,4-dihydro-1H-pyrazino[2,1-b]quinazoline-3,6-diones (1b-m) in which the alkyl chain is (CH(2))(n), n = 1-3, behave as glycine templates giving by treatment with [hydroxy(tosyloxy)iodo]benzene in ethyl acetate cis-1-tosyloxy derivatives. When these compounds contain electron-rich aryl substituents with n = 2, they spontaneously cyclize through intramolecular
对映体纯的4-取代的2-芳烷基-2,4-二氢-1H-吡嗪并[2,1-b]喹唑啉-3,6-二酮(1b-m),其中烷基链为(CH(2))( n),n = 1-3,表现为甘氨酸模板,通过在乙酸乙酯的cis-1-tosyloxy衍生物中用[羟基(tosyloxy)碘]苯处理得到。当这些化合物包含n = 2的富电子芳基取代基时,它们通过分子内Friedel-Crafts型非对映选择性反应自发环化,生成五环或六环化合物。否则,它们通过溶剂分解得到顺式-1-烷氧基衍生物,如果n = 2、3,则可以在第二步中在酸中环化。所有这些反应必须通过类似于S(N)1机理的N-酰氨基发生。 。1-烷氧基-2-芳基甲基衍生物不愿环化,使反式-1-羟基化合物成为唯一的分离反应产物。