zed asymmetric SNAr reactions provide unique contribution to the catalyticasymmetric α‐arylations of carbonyl compounds to produce biologically active α‐aryl carbonyl compounds, the electrophiles were limited to arenes bearing strong electron‐withdrawing groups, such as a nitro group. To overcome this limitation, we examined the asymmetric SNAr reactions of α‐amino acid derivatives with arene chromium
尽管相转移催化的不对称S N Ar反应为羰基化合物的催化不对称α-芳基化反应产生了生物活性的α-芳基羰基化合物做出了独特贡献,但亲电试剂仅限于带有强吸电子基团的芳烃,例如硝基。为了克服这一局限性,我们研究了α-氨基酸衍生物与衍生自氟代芳烃的芳烃铬配合物(包括含给电子取代基的芳烃铬配合物)的不对称S N Ar反应。联萘改性的手性相转移催化剂可有效地促进芳基化反应,从而生成相应的α,α-二取代的α-氨基酸,其中包含具有高对映选择性的各种芳族取代基。
Lithiation of 2-, 3-, and 4-fluoroanisole(tricarbonyl)chromium(0) complexes: a reversal of normal regiocontrol
作者:John P. Gilday、David A. Widdowson
DOI:10.1039/c39860001235
日期:——
Lithiation of tricarbonyl(fluoroanisole)chromium(0) complexes occurs exclusively ortho to the fluorine atom, not the oxygen atom as observed in the uncomplexed arenes; the X-ray structure of complex (1) shows that the specificity is not caused by steric inhibition of lithium base co-ordination by oxygen.