Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States.
Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States.
J Am Chem Soc. 2021 Jun 30;143(25):9343-9349. doi: 10.1021/jacs.1c05212. Epub 2021 Jun 21.
The first systematic study of simple nitronate nucleophiles in iridium-catalyzed allylic alkylation is described. Using a tol-BINAP-modified π-allyliridium ,-benzoate catalyst, α,α-disubstituted nitronates substitute racemic branched alkyl-substituted allylic acetates, thus providing entry to β-stereogenic α-quaternary primary amines. DFT calculations reveal early transition states that render the reaction less sensitive to steric effects and distinct trans-effects of diastereomeric chiral-at-iridium π-allyl complexes that facilitate formation of congested tertiary-quaternary C-C bonds.
描述了首例铱催化烯丙基烷基化反应中简单硝酮亲核试剂的系统研究。使用托-BINAP 修饰的π-烯丙基铱-苯甲酸盐催化剂，α,α-二取代硝酮取代外消旋支链烷基取代的烯丙基乙酸酯，从而为 β-手性 α-季铵基伯胺提供了入口。DFT 计算揭示了早期过渡态，使反应对立体效应的敏感性降低，以及手性铱π-烯丙基配合物的独特反式效应，有利于形成拥挤的三级-四级 C-C 键。
