Alkynyl<i>N</i>-Nosylhydrazones: Easy Decomposition to Alknynl Diazomethanes and Application in Allene Synthesis
作者:Yang Yang、Zhaohong Liu、Alessio Porta、Giuseppe Zanoni、Xihe Bi
DOI:10.1002/chem.201701462
日期:2017.7.6
reaction with boronic acids under metal-free conditions is reported, giving rise to a wide array of di- and trisubstituted allenes. Preliminary mechanistic investigations demonstrated that γ-protodeboration of propargyl boric acid was responsible for the initial allene formation. This methodology based on the nosyl group allows for novel transformations that involve an alkynylcarbene transient species
“One-Pot” Access to 4<i>H</i>-Chromenes with Formation of a Chiral Quaternary Stereogenic Center by a Highly Enantioselective Iminium-allenamine Involved Oxa-Michael−Aldol Cascade
作者:Chunliang Liu、Xinshuai Zhang、Rui Wang、Wei Wang
DOI:10.1021/ol102096s
日期:2010.11.5
organocatalytic highlyenantioselectivecascade Michael−aldol reaction has been developed in high yields under mild reaction conditions. The “one-pot” process affords an efficient approach to the synthetically and biologically important chiral4H-chromenes bearing a quaternary stereogenic center. The study significantly expands the scope of less explored organocatalytic iminium-allenamine chemistry.
Iminium-Allenamine Cascade Catalysis: One-Pot Access to Chiral 4H-Chromenes by a Highly Enantioselective Michael-Michael Sequence
作者:Xinshuai Zhang、Shilei Zhang、Wei Wang
DOI:10.1002/anie.200906050
日期:2010.2.15
Taking the Michael‐Michael: A cascadeMichael–Michael reaction of aryl or alkyl alkynals, involving an unprecedented iminium–allenaminesequence, is efficiently catalyzed by a chiral diphenylprolinol TBDMS ether, and affords highly functionalized 4H‐chromenes in high yields. TBDMS=tert‐butyldimethylsilyl.
An Organocatalytic Cascade Approach toward Polysubstituted Quinolines and Chiral 1,4-Dihydroquinolines-Unanticipated Effect of N-Protecting Groups
作者:Xinshuai Zhang、Xixi Song、Hao Li、Shilei Zhang、Xiaobei Chen、Xinhong Yu、Wei Wang
DOI:10.1002/anie.201202161
日期:2012.7.16
of a divergent organocatalytic aza‐Michael/aldol cascade process towardquinolines and 1,4‐dihydroquinolines depends on the choice of the N‐protecting group (see scheme; TEA=triethylamine, TMS=trimethylsilyl). Use of an electron‐donating sulfonyl group results in an unanticipated aza‐Michael/aldol/aromatization cascade to give polysubstitutedquinolines (right). In contrast, chiral 1,4‐dihydroquinolines
Enantioselective N-Heterocyclic Carbene-Catalyzed Kinetic Resolution of Anilides
作者:Jianbo Bie、Ming Lang、Jian Wang
DOI:10.1021/acs.orglett.8b02538
日期:2018.9.21
The N-heterocyclic carbene (NHC)-catalyzed enantioselectivekineticresolution of anilides (a kind of hemiaminals) is reported. Upon exposure to the reaction in the presence of an NHC precatalyst and base, catalytic C–O bond formation occurs, providing axially chiral isoindolinones in high yields with excellent enantioselectivities.