Regioselective Control in the Reactions of α-Aminoalkylcuprates with Allylic Substrates
作者:R. Dieter、Sadanandan Velu、Lois Nice
DOI:10.1055/s-1997-1544
日期:1997.9
Organocuprate reagents prepared from α-aminoalkyllithium reagents and CuCN react with allylic electrophiles to afford homoallylic amines. Allylic sulfides of benzothiazole-2-thiol give exclusively substitution products without rearrangement while cuprate reagents prepared from primary α-aminoalkyl ligands react with allylic bromides to give rearranged substitution products with modest regioselectivity. Chemical yields and regioselectivities are dependent upon solvent, substrate leaving group, added LiCl salt, and α-aminoalkyl ligand.
SN2-selective Grignard coupling with primary allylic diphenylphosphates was successfully achieved using Ni or Fe catalyst. In sharp contrast, a catalytic amount of CuCN·2LiCl promoted a SN2′-selective coupling reaction. In the presence of the copper catalyst, stereochemically homogeneous γ- disubstituted allyl Grignardreagents reacted at the less substituted allylic terminus (α-position) with an allylic diphenylphosphate
使用Ni或Fe催化剂成功地实现了S N 2-选择性格利雅(Grignard)与伯烯丙基二苯基磷酸酯的偶联。与之形成鲜明对比的是,催化量的CuCN·2LiCl促进了S N 2'-选择性偶联反应。在铜催化剂的存在下,立体化学均一的γ-二取代的烯丙基格氏试剂在较少取代的烯丙基末端(α-位)与烯丙基磷酸二苯酯选择性地反应,而不会失去双键的几何形状。
Ranu, Brindaban C.; Das, Arijit, Journal of the Indian Chemical Society, 2003, vol. 80, # 11, p. 1063 - 1064
作者:Ranu, Brindaban C.、Das, Arijit
DOI:——
日期:——
An Improved Method for Lewis Acid Catalyzed Phosphoryl Transfer with Ti(<i>t</i>-BuO)<sub>4</sub>
作者:Simon Jones、Dimitrios Selitsianos、Kate J. Thompson、Steven M. Toms
DOI:10.1021/jo034331g
日期:2003.6.1
Several inorganic esters have been evaluated as phosphoryl transfer catalysts. Of these, Ti(t-BuO)(4) was found to be the most effective catalyst giving excellent yields of the desired phosphate esters. The loading of the catalyst could be reduced to a little as 5 mol % for a majority of substrates with no loss in the yield of product. This methodology is significantly more versatile than using TiCl4 and is suitable for the phosphorylation of more complex carbohydrates and molecules of biological interest.
ARAKI, SHUKI;OHMORI, KOICHI;BUTSUGAN, YASUO, SYNTHESIS, BRD, 1984, N 10, 841-842