Propargyl Hydrazides: Synthesis and Conversion Into Pyrazoles Through Hydroamination
作者:Mitsuhiro Yoshimatsu、Katsuki Ohta、Nami Takahashi
DOI:10.1002/chem.201202828
日期:2012.12.3
Pyrazoles direct: Propargyl alcohols undergo hydrazination when treated with p‐tosyl hydrazide in the presence of catalytic amounts of either Sc(OTf)3 or La(OTf)3 (see scheme; Tf=trifluoromethanesulfonyl). Propargyl hydrazides are converted into either N‐tosyl or N‐H pyrazoles when treated with an acid or a base, respectively. The one‐step acid‐catalyzed hydrazination/cyclization of propargyl alcohols
直接吡唑:在催化量的Sc(OTf)3或La(OTf)3存在下,用对甲苯磺酰基酰肼处理时,炔丙醇会发生酰化作用(见方案; Tf =三氟甲磺酰基)。分别用酸或碱处理时,炔丙基酰肼可分别转化为N-甲苯磺酰基或N- H吡唑。炔丙醇的一步酸催化肼化/环化反应可直接获得高产率的吡唑。