Guanidine–Copper Complex Catalyzed Allylic Borylation for the Enantioconvergent Synthesis of Tertiary Cyclic Allylboronates
作者:Yicen Ge、Xi‐Yang Cui、Siu Min Tan、Huan Jiang、Jingyun Ren、Nicholas Lee、Richmond Lee、Choon‐Hong Tan
DOI:10.1002/anie.201813490
日期:2019.2.18
allylboronates from racemic allylic bromides was achieved by using a guanidine–copper catalyst. The allylboronates were obtained with high γ/α regioselectivities (up to 99:1) and enantioselectivities (up to 99 % ee), and could be further transformed into diverse functionalized allylic compounds without erosion of optical purity. Experimental and DFT mechanistic studies support an SN2′ borylation process
通过使用胍-铜催化剂,由外消旋烯丙基溴对映体合成手性环状烯丙基硼酸酯。获得的烯丙基硼酸酯具有高的γ/α区域选择性(高达99:1)和对映选择性(高达99%ee),并且可以进一步转化为多种功能化的烯丙基化合物,而不会降低光学纯度。实验和DFT机理研究支持单齿胍-铜(I)配合物催化的S N 2'硼化过程,该过程通过特殊的直接对映体转化机理进行。
Practical, Broadly Applicable, α-Selective, <i>Z</i>-Selective, Diastereoselective, and Enantioselective Addition of Allylboron Compounds to Mono-, Di-, Tri-, and Polyfluoroalkyl Ketones
作者:Farid W. van der Mei、Changming Qin、Ryan J. Morrison、Amir H. Hoveyda
DOI:10.1021/jacs.7b05011
日期:2017.7.5
accessible unsaturated organoboron compounds serve as reagents. Transformations were performed with 0.5-2.5 mol % of a boron-based catalyst, generated in situ from a readily accessible valine-derived aminophenol and a Z- or an E-γ-substituted boronic acid pinacol ester. With a Z organoboron reagent, additions to trifluoromethyl and polyfluoroalkyl ketones proceeded in 80-98% yield, 97:3 to >98:2 α:γ selectivity
A method for the synthesis of alpha-chiral allylboronates featuring the Cu(I)-catalyzed enantioselective substitution of readily available allylic carbonates with a diboron is described. Using this method, various alpha-chiral allylboronates, including functionalized allylboronates, were successfully synthesized, with high enantiomeric purity.
Catalytic Enantioselective Preparation of α-Substituted Allylboronates: One-Pot Addition to Functionalized Aldehydes and a Route to Chiral Allylic Trifluoroborate Reagents