Asymmetric Hydrogenation of Hydrazones with Chiral Boranes
作者:Kuai Yu、Wei Meng、Xiangqing Feng、Haifeng Du
DOI:10.1021/acs.orglett.3c00843
日期:2023.5.26
An enantioselective metal-free hydrogenation of hydrazones has been realized successfully using chiral boranes as catalysts, producing a range of optically active hydrazines in 87–99% yields with 75–93% ee’s. The bulky 2,2,6,6-tetramethylpiperidinyl moiety was found to be essential for achieving the high enantioselectivities.
使用手性硼烷作为催化剂成功实现了腙的对映选择性无金属氢化,以 87-99% 的产率和 75-93% ee 产生了一系列光学活性肼。发现庞大的 2,2,6,6-四甲基哌啶基部分对于实现高对映选择性至关重要。
An organocatalyzed Fischer indolization is established by combining 2,2′-biphenol (10 mol%) and B(OH)3 (30 mol%) as weak, readily available, and easy-to-handle acids. The inclusion of MgSO4, which efficiently scavenges NH3 (a possible acid catalyst poison), appears to be key to the success of this process. The corresponding indoles are obtained in yields of up to 91% using this method.y