Zinc Catalyzed and Mediated Propargylations with Propargyl Boronates
摘要:
The utility of allenyl and propargyl boronates for the propargylation of aldehydes and ketones mediated by zinc is presented. The reaction Is catalytic in zinc with allenyl or propargyl borolanes. The propargylation with crystalline and air-stable propargyl diethanolamine boronates was also achieved. A catalytic cycle is proposed, and preliminary mechanistic studies are discussed.
Silver-catalysed intramolecular hydroamination of alkynes with trichloroacetimidates
作者:Valerie H. L. Wong、T. S. Andy Hor、King Kuok (Mimi) Hii
DOI:10.1039/c3cc45500a
日期:——
Silver(I) complexes catalyse the intramolecular addition of trichloroacetimidates to alkynes. In the absence of a ligand, the selectivity of the reaction is dependent upon the nature of the counter-anion and solvent. The introduction of non-chelating nitrogeneous ligands suppresses competitive Brønsted acid catalysis, improving the yield and selectivity of the reaction.
Photoredox Propargylation of Aldehydes Catalytic in Titanium
作者:Francesco Calogero、Andrea Gualandi、Marco Di Matteo、Simone Potenti、Andrea Fermi、Giacomo Bergamini、Pier Giorgio Cozzi
DOI:10.1021/acs.joc.1c00521
日期:2021.5.7
A practical and effective photoredox propargylation of aldehydes promoted by 10 mol % of [Cp2TiCl2] is presented. No stoichiometric metals or scavengers are used for the process. A catalytic amount of the cheap and simply prepared organic dye 3DPAFIPN is used as the reductant for titanium. The reaction displayed a broad scope, and no traces of allenyl isomers were detected for simple propargyl bromide
A facile lipase-catalyzed KR approach toward enantiomerically enriched homopropargyl alcohols
作者:Paweł Borowiecki、Maciej Dranka
DOI:10.1016/j.bioorg.2019.01.050
日期:2019.12
(E ≫ 500) furnishing both resolution products of the racemic 1-phenylbut-3-yn-1-ol in highly enantiomerically enriched form (up > 99% ee). Variable reaction parameters, such as the acyl-group donor reagent as well as solvent, were additionally screened to establish their impact on the stereochemical outcome. For optimal biocatalytic systems established with model substrate, the enzymatic transformations were
A novel copper‐catalyzed one‐pot functionalization of homopropargylic alcohols that involves trifluoromethylation, aryl migration, and formation of a carbonyl moiety has been developed. This reaction constitutes the first direct conversion of homopropargylic alcohols into CF3‐containing 3‐butenal or 3‐buten‐1‐one derivatives in a regioselective manner. Mechanistic studies indicate that the 1,4‐aryl
Electrophilic Cyclization and Intermolecular Acetalation of 2-(4-Hydroxybut-1-yn-1-yl)benzaldehydes: Synthesis of Diiodinated Diepoxydibenzo[<i>c</i>,<i>k</i>][1,9]dioxacyclohexadecines
strategy for the preparation of diiodinated diepoxydibenzo[c,k][1,9]dioxacyclohexadecines from readily available 2-(4-hydroxybut-1-yn-1-yl)benzaldehydes through electrophile-triggered tandem cyclization/intermolecular acetalation sequence has been presented. The electrophilic macrocyclization can be performed under mild conditions and in up to gram quantities. Moreover, palladium-catalyzed coupling and