Expanding the Scope of Mn(OAc)3-Mediated Cyclizations: Synthesis of the Tetracyclic Core of Tronocarpine
摘要:
Pyrroles, indoles, and surprisingly, indolines, when equipped with a pendant malonyl group on the nitrogen atom, were effective substrates in a Mn(III)-mediated oxidative cyclization reaction, yielding the 1,2-annulated products in good to excellent yields. When indole acetonitrile was used as a substrate this method provided a rapid synthesis of a tetracyclic tronocarpine subunit.
C–H Alkenylation of Heteroarenes: Mechanism, Rate, and Selectivity Changes Enabled by Thioether Ligands
作者:Bradley J. Gorsline、Long Wang、Peng Ren、Brad P. Carrow
DOI:10.1021/jacs.7b03887
日期:2017.7.19
catalytic intermediate in these reactions may also account for unusual catalyst-controlled site selectivity wherein C–H alkenylation of five-atom heteroarenes can occur under electronic control with thioether ligands even when this necessarily involves reaction at a more hindered C–H bond. The thioether effect also enables short reaction times under mild conditions for many O-, S-, and N-heteroarenes (55 examples)
A novel electron‐donor–acceptor (EDA) complex‐mediated direct CH trifluoromethylation of arenes with Umemoto’s reagent has been developed. This transformation has been enabled by an unprecedented EDA complex formed by Umemoto’s reagent and an amine, which was supported by experiments and theoretical calculations. The radical‐based methodology presented here allows to access highly‐functionalized trifluoromethyl
Synthesis of pyrrolizin-3-ones by flash vacuum pyrolysis of pyrrol-2-ylmethylidene Meldrum’s acid derivatives and 3-(pyrrol-2-yl)propenoic esters
作者:Shirley E. Campbell、Murray C. Comer、Paul A. Derbyshire、Xavier L. M. Despinoy、Hamish McNab、Roderick Morrison、Craig C. Sommerville、Craig Thornley
DOI:10.1039/a701749i
日期:——
Monosubstituted pyrrolizin-3-ones 1 with substituents at the 1-, 5-,
6- or 7-positions are prepared in excellent yield by flash vacuum
pyrolysis (FVP) of appropriate Meldrumâs acid derivatives 2. The
mechanism involves formation of the pyrrol-2-ylmethylideneketene 29,
which can also be generated thermally from 3-(pyrrol-2-yl)propenoate
esters (e.g. 30). This alternative route has been used to make
a range of 2-substituted pyrrolizin-3-ones, again in excellent yield.
The 3-oxo-3H-pyrrolizine-2-carboxylic acid 42 could not be made
in this way owing to facile decarboxylation to pyrrolizinone 1, and
extension to the formation of the azaazulenone 48 was again
unsuccessful.
Reduction of α - substituted succinonitriles with diisobutylaluminum hydride: a facile method for the synthesis of 3-substituted pyrroles
作者:James H. Babler、Kenneth P. Spina
DOI:10.1016/s0040-4039(01)81137-0
日期:1984.1
Treatment of four representative α - substituted succinonitriles (2) with diisobutylaluminumhydride, followed by hydrolysis of each reaction mixture with aqueous sodium dihydrogen phosphate, afforded 3-substituted pyrroles (4) in approximately 50% yield.
Hypervalent iodine(III): selective and efficient single-electron-transfer (SET) oxidizing agent
作者:Toshifumi Dohi、Motoki Ito、Nobutaka Yamaoka、Koji Morimoto、Hiromichi Fujioka、Yasuyuki Kita
DOI:10.1016/j.tet.2009.10.040
日期:2009.12
ethers, affording the corresponding aromatic cation radicals. Since then, hypervalent iodine(III) has been utilized as a selective and efficient SET oxidizingagent that enables a variety of direct C–H functionalizations of aromatic rings in electron-rich arenes under mild conditions. We have now extended the original method to work in a series of heteroaromatic compounds such as thiophenes, pyrroles,