Stable Enols of Carboxylic Esters. The Poly(methoxycarbonyl)cyclopentadiene Systems
作者:Yi Xiong Lei、Giovanni Cerioni、Zvi Rappoport
DOI:10.1021/jo000046a
日期:2000.6.1
C(5)H(6)(-)(n)()(CO(2)Me)(n)(), n = 5 (Cp-5), n = 4 (Cp-4), n = 3 (1, 2,4-; Cp-3) and n = 2 (1,2-; 1,2-Cp-2-I) were investigated. The X-ray diffractions of Cp-5 (known), Cp-4, and Cp-3 showed an enol of ester structure in the solid state. The enolic hydrogen forms a symmetrical hydrogen bond to a neighboring ester carbonyl, so that the vicinal "enolic" CO(2)Me groups in the 1, 2-C(=CO(2)Me)-C(CO(2)Me)(4) moiety
聚(甲氧羰基)环戊二烯C(5)H(6)(-)(n)()(CO(2)Me)(n)()的结构,n = 5(Cp-5),n = 4 (Cp-4),n = 3(1、2,4-; Cp-3)和n = 2(1,2-; 1,2-Cp-2-I)。Cp-5(已知),Cp-4和Cp-3的X射线衍射显示固态的酯结构的烯醇。烯醇氢与相邻的酯羰基形成对称氢键,因此在1,2-C(= CO(2)Me)-C(CO(2)Me )(4)部分相同。三种烯醇的相关X射线参数相似。Cp-3-Cp-5的CP-MAS光谱通常类似于CDCl(3)中的(13)C NMR光谱,除了一些差异大多<1 ppm。CDCl(3)中Cp-3-Cp-5的(1)H,(13)C和(17)O NMR光谱与氢键烯醇的光谱一致。最具特征的是分别在19.7-20.1和221-225 ppm处的OH基团的(1)H和(17)O信号。将质子加到1,2-双(甲氧基羰基)环戊