A catalytic enantioselective synthetic strategy for the aryl-substituted all-carbon quaternary stereocenters of bioactive hydrodibenzofuran alkaloids was achieved by the Michael addition reaction of α-cyano ketones and acrylates using a chiral tertiary amine–thiourea catalyst. This method can tolerate steric bulkiness and multiple functional groups, and 32 Michael adducts were prepared in good to excellent
2-aryl-3-arylazoacrylonitriles are synthesized while attempting the intramolecular N-arylation of 5-aminopyrazoles, using the hypervalent iodine reagent. The synthesis involves phenyl iodine diacetate-assisted ringopening of 5-aminopyrazoles at room temperature. A plausible mechanism for the formation of azoalkenes is proposed.
A copper-catalysed intramolecular N-arylation of 5-aminopyrazoles is demonstrated for the first time. Highly substituted pyrazolo[3,4-b]indoles are synthesized. In particular, the indole core is decorated with halogens and alkyl and methoxy groups. Furthermore, a selectiveN-arylation of unsymmetrical diaryl bromide containing pyrazoles is exemplified, resulting in valuable pyrazolo[1,5-a]benzimidazoles
首次证明了铜催化的5-氨基吡唑的分子内N-芳基化。合成了高度取代的吡唑并[3,4- b ]吲哚。特别地,吲哚核被卤素以及烷基和甲氧基装饰。此外,举例说明了含不对称二芳基溴的吡唑的选择性N-芳基化,得到了有价值的吡唑并[1,5- a ]苯并咪唑。
Enantioselective Synthesis of N−N Bisindole Atropisomers
作者:Peng Zhang、Qi Xu、Xiao‐Mei Wang、Jia Feng、Chuan‐Jun Lu、Yingzi Li、Ren‐Rong Liu
DOI:10.1002/anie.202212101
日期:2022.11.2
An enantioselectivesynthesis of N−Nbisindoleatropisomers based on the de novo construction of one indole skeleton is presented. A wide variety of N−N axially chiral bisindoles were obtained in good yields with excellent enantioselectivities. Structurally diverse indole-pyrrole, indole-carbazole and non-biaryl-indole atropisomers possessing a chiral N−N axis were accessed using this protocol.
We present a new strategy for the dearomatized hydroxylation of 5-aminopyrazoles using a hypervalent iodine reagent at room temperature. This method produces a series of 4-hydroxy-5-iminopyrazolines with good to excellent yields within 2 hours. Additionally, we demonstrate a domino reaction for the synthesis of 4-hydroxy-pyrazolones. Mechanistic studies indicate that the dearomatization proceeds through