Origin of<sup>13</sup>C complexation shifts in the adduct formation of 2-butyl phenyl ethers with a dirhodium tetracarboxylate complex
作者:Edison Díaz Gómez、Helmut Duddeck
DOI:10.1002/mrc.2116
日期:2008.1
Complexation of the oxygen atom in 2‐butyl phenyl ethers to a rhodium atom of the dirhodium tetracarboxylate Rh(II)2[(R)‐(+)‐MTPA]4(Rh*, MTPA‐H = methoxytrifluoromethylphenylacetic acid ≡ Mosher's acid) deshields an sp3‐hybridized 13C nucleus directly bonded to the ether oxygen; apparently, the inductive effect of the oxygen is enhanced when it is complexed to the rhodium atom. On the other hand, deshielding
2-丁基苯基醚中的氧原子与四羧酸二铑 Rh(II)2[(R)-(+)-MTPA]4(Rh*, MTPA-H = 甲氧基三氟甲基苯乙酸 ≡ Mosher 酸) 的铑原子络合去屏蔽直接与醚氧结合的 sp3 杂化 13C 核;显然,当氧与铑原子络合时,它的感应效应会增强。另一方面,芳族同碳(α位)的去屏蔽络合位移很小,但邻位和对位碳信号受氧共振效应的影响。这种效果可以通过苯环上的其他取代基来调节。反过来,这种共振调制与施加在脂肪族α-碳原子上的感应效应的大小呈线性相关。对于大多数化合物,可以观察到 13C 信号下的非对映体分散效应,表明在此类醚中可能发生对映分化。版权所有 © 2008 John Wiley & Sons, Ltd.