CeCl3·7H2O/IBX-promoted oxidation of 3-alkylindoles to 3-hydroxyoxindoles
摘要:
3-Alkylindoles undergo smooth oxidation with IBX in the presence of CeCl(3 center dot)7H(2)O in aqueous acetonitrile at ambient temperature to afford the corresponding 3-hydroxyoxindoles in high yields. This method is very useful for the direct preparation of 3-hydroxyoxindoles from 3-alkylindoles. Operational simplicity, mild and neutral reaction conditions in aqueous solution are the key features of this protocol. (c) 2007 Published by Elsevier Ltd.
Catalytic Enantioselective Synthesis of Tetrahydocarbazoles and Exocyclic Pictet–Spengler-Type Reactions
作者:Casper L. Hansen、Ragnhild G. Ohm、Lasse B. Olsen、Erhad Ascic、David Tanner、Thomas E. Nielsen
DOI:10.1021/acs.orglett.6b02718
日期:2016.12.2
developed. The strategy relies on two types of 6-exo-trig cyclization of 3-substituted indole substrates. Enantioselective domino Friedel–Crafts-type reactions leading to THCAs can be catalyzed by chiral phosphoric acid derivatives (with up to >99% ee), and the first examples of exocyclic Pictet–Spenglerreactions to form THCAs are reported.
Direct C–H Cyanation by ICN Formed <i>In Situ</i>: Nannozinone B
作者:Paul Wienecke、Hans-Dieter Arndt
DOI:10.1021/acs.orglett.3c00176
日期:2023.2.24
A novel method for C–H cyanation of different pyrans, pyrroles, indoles, and acyclic nucleophilic double bonds using TMSCN, NIS, and Zn(OTf)2 as a catalyst is described. The transformation is conducted under mild conditions tolerating a variety of functional groups. Zn(OTf)2 is likely to serve a dual catalytic role as an activator for TMSCN and for the cyanogen iodide generated in situ. Optimization
Enantioselective Friedel−Crafts Alkylations Catalyzed by Bis(oxazolinyl)pyridine−Scandium(III) Triflate Complexes
作者:David A. Evans、Keith R. Fandrick、Hyun-Ji Song、Karl A. Scheidt、Risheng Xu
DOI:10.1021/ja072976i
日期:2007.8.1
The enantioselective Friedel-Crafts addition of a variety of indoles catalyzed by bis(oxazolinyl)pyridine-scandium(III) triflate complexes (Sc(III)-pybox) was accomplished utilizing a series of beta-substituted alpha,beta-unsaturated phosphonates and alpha,beta-unsaturated 2-acyl imidazoles. The acyl phosphonate products were efficiently transformed into esters and amides, whereas the acyl imidazole adducts were converted to a broader spectrum of functionalities such as esters, amides, carboxylic acids, ketones, and aldehydes. The sense of stereoinduction and level of enantioselectivity were found to be functions of the size of the substrate employed, the substitution on the ligand, and the catalyst loading. Molecular modeling of the catalyst with the bound substrates was performed based on the crystal structures of the catalyst complexes and the sense of stereoinduction observed in the addition reaction. Nonlinear effects over a range of catalyst concentrations implicate a mononuclear complex as the active catalyst.