Wu Qing-Feng, Wang Xiao-Bing, Shen Peng-Xiang, Yu Jin-Quan
Department of Chemistry, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, California 92037.
ACS Catal. 2018 Mar 2;8(3):2577-2584. doi: 10.1021/acscatal.8b00069. Epub 2018 Feb 5.
Chiral mono--protected aminomethyl oxazoline (MPAO) ligands are found to promote enantioselective C-H arylation and vinylation of the cyclobutyl carboxylic acid derivatives Pd(II)/Pd(IV) redox catalysis. This ligand scaffold overcame two important limitations of the previous MPAHA (mono--protected α-amino--methylhydroxamic acid) ligands-enabled asymmetric C-H activation/C-C coupling reactions of cyclic carboxylic amides through Pd(II)/Pd(0) catalysis: substrates containing α-hydrogen atoms are not compatible; vinylation has not been developed. Sequential C-H arylation and vinylation of cyclobutanes are also accomplished to construct three consecutive chiral centers on the crowded cyclobutane rings, rendering this reaction highly versatile for the preparation of chiral cyclobutanes.
手性单保护氨甲基恶唑啉（MPAO）配体被发现可通过Pd（II）/Pd（IV）氧化还原催化促进环丁基羧酸衍生物的对映选择性C-H芳基化和乙烯基化反应。这种配体骨架克服了先前MPAHA（单保护α-氨基甲基异羟肟酸）配体通过Pd（II）/Pd（0）催化实现环状羧酰胺不对称C-H活化/C-C偶联反应的两个重要局限性：含α-氢原子的底物不相容；乙烯基化反应尚未开发。环丁烷的顺序C-H芳基化和乙烯基化反应也得以实现，从而在拥挤的环丁烷环上构建了三个连续的手性中心，使得该反应在制备手性环丁烷方面具有高度的通用性。
