One-Pot Synthesis of Pyrazoles through a Four-Step Cascade Sequence
作者:Lu Hao、Jun-Jie Hong、Jun Zhu、Zhuang-Ping Zhan
DOI:10.1002/chem.201204322
日期:2013.4.26
A one‐potsynthesis of 3,4,5‐ and 1,3,5‐pyrazoles from tertiary propargylic alcohols and para‐tolylsulfonohydrazide has been accomplished. The pyrazoles are formed through a four‐step cascade sequence, including FeCl3‐catalyzed propargylic substitution, aza‐Meyer–Schuster rearrangement, base‐mediated 6π electrocyclization, and thermal [1,5] sigmatropic shift. In this reaction, the 3,4,5‐ and 1,3,5‐pyrazoles
Cross-Coupling of Meyer–Schuster Intermediates under Dual Gold–Photoredox Catalysis
作者:Jiwon Um、Hokeun Yun、Seunghoon Shin
DOI:10.1021/acs.orglett.5b03531
日期:2016.2.5
Under dual gold/photoredoxcatalyticconditions, intermediates from the Meyer–Schuster rearrangement underwent an efficient cross-coupling with arene diazoniumsalts, leading to α-arylated enones. Diazoniumsalts assisted the dissociation of the propargyl hydroxyl group by forming alkoxydiazenes in the Meyer–Schuster rearrangement, and the coupling was proposed to proceed through an allenyl methyl
An iodine(III)-catalyzed general method for the synthesis of fully functionalized NH-pyrazoles and isoxazoles from α,β-unsaturated hydrazones and oximes, respectively, via cyclization/1,2-aryl shift/aromatization/detosylation, has been developed. The reaction progresses through an anti-Baldwin 5-endo-trig cyclization. It gives direct access to an advanced intermediate for the preparation of valdecoxib