derivative in 74% yield with 90% de (SP diastereoisomer) using the base generated from CdCl2 and Li(TMP) (3 equiv), and in 85% yield with 91% de (SP diastereoisomer) through a double asymmetric induction using a chiral lithium–zinc base generated from ZnCl2·TMEDA and lithium (R)-bis(1-phenylethyl)amide (4 equiv). In contrast, using a combination prepared from ZnCl2 and Li(TMP) (4 equiv) with the ferrocene carboxylate
A mixed lithiumâcadmium amide and a combination of lithium and zinc amides were reacted with a range of ferrocenes; deprotonative mono- or dimetallation in general occurred chemoselectively at room temperature, as evidenced by subsequent quenching with iodine.
alkyl-containing lithium zincates, 1 : 1 mixtures of lithium and zinc amides were tested. Chiral (H-exo-born-R or H-endo-born-S) or/and achiral (lithium 2,2,6,6-tetramethylpiperidide or lithium diisopropylamide) secondaryamines gave good results, the best (81% yield and 44% ee in favor of the RP enantiomer) being obtained by using (endo-born-S)3ZnLi in THF at room temperature. Among other secondaryamines also
描述了使用混合锂-锌或锂-镉碱对二茂铁羧酸烷基酯 (FcCO 2 R) 进行对映选择性去金属化。以FcCO 2 Me为底物,由外-(α R )-或内-(α S ) -N- (α-苯乙基)冰片胺( H-外-本-R或H- )制备手性烷基氨基锌酸锂内生-S ) 进行了测试;最好的结果(27%产率和62%ee的赞成的[R P对映体)通过使用卜得到2(内切-born-S ) ZnLi 在四氢呋喃 (THF) 中在 -30 °C 下碘分解。由于 FcCO 2 Me 与含烷基的锌酸锂的相容性低,因此测试了氨基化锂和氨基化锌的 1:1 混合物。手性(H- exo- born- R或H- endo- born- S)或/和非手性(2,2,6,6-四甲基哌啶锂或二异丙基氨基锂)仲胺得到了很好的结果,最好的(81%的产率和44% ee 有利于R P对映异构体)是通过在室温下在 THF 中使用(内生S)3 ZnLi
On the
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‐Arylation of Acetamide Using 2‐, 3‐ and 1’‐Substituted Iodoferrocenes**
作者:Lingaswamy Kadari、William Erb、Yury S. Halauko、Oleg A. Ivashkevich、Vadim E. Matulis、Dmitry Lyakhov、Thierry Roisnel、Palakodety Radha Krishna、Florence Mongin
DOI:10.1002/ejic.202000904
日期:2021.1.26
range of original 1,2‐, 1,3‐ and 1,1’‐disubstituted ferrocenes to be obtained. The results were compared as a function of the substituent and its position on the ring. DFT calculations revealed higher activation barrier for the oxidative addition in the ferrocene series when compared with classical planar aromatics. Structure‐property relationships were applied to rationalize the reactivity of the different
Induction of Planar Chirality Using Asymmetric Click Chemistry by a Novel Desymmetrisation of 1,3-Bisalkynyl Ferrocenes
作者:Adam J. Wright、David L. Hughes、Phillip C. Bulman Page、G. Richard Stephenson
DOI:10.1002/ejoc.201901192
日期:2019.11.24
Asymmetric click chemistry is used to induce planar stereogenicity in prochiral ferrocenyl diynes, giving products in up to 99.5 % ee. Asymmetricinduction and kinetic resolution studies on a novel library of prochiral 1,2,3‐trisubstituted bis‐alkynylferrocenes are reported.