Palladium-Catalyzed Asymmetric Amination and Imidation of 2,3-Allenyl Phosphates
摘要:
[GRAPHICS]Asymmetric amination of 2,3-allenyl phosphates with nitrogen nucleophiles such as amines, hydroxylamines, and imides can be performed efficiently using a combination of zerovalent palladium complexes and SEGPHOS or MeOBlPHEP ligand, affording the corresponding optically active 1-aminated derivatives with enantiomeric excess of up to 97% ee.
Enantioselective Synthesis of Spiropentanes from Hydroxymethylallenes
作者:André B. Charette、Eric Jolicoeur、Gregory A. S. Bydlinski
DOI:10.1021/ol0165140
日期:2001.10.1
[reaction: see text]. Hydroxymethylallenes are efficiently converted to the corresponding spiropentanes in high yields and enantiomeric ratios upon treatment with Zn(CH2I)2 and dioxaborolane ligand 1. The reaction also proceeds with complete diastereocontrol. The application of this methodology to the synthesis of spiropentaneacetic acid is also presented.
Nickel-Catalyzed Chemo- and Enantioselective Coupling between Cyclobutanones and Allenes: Rapid Synthesis of [3.2.2] Bicycles
作者:Xuan Zhou、Guangbin Dong
DOI:10.1002/anie.201609489
日期:2016.11.21
Herein an intramolecular nickel‐catalyzed (4+2) coupling between cyclobutanones and allenes, by C−C cleavage, is reported. The reaction provides a distinct approach for accessing [3.2.2] bicyclic scaffolds which are challenging to prepare through conventional approaches. The reaction is efficient, chemoselective, and pH/redox neutral. Room temperature conditions and low catalyst loadings can be adopted
The regio- and stereochemical course of reductive cross-coupling reactions between 1,3-disubstituted allenes and vinylsilanes: synthesis of (Z)-dienes
作者:Allan U. Barlan、Glenn C. Micalizio
DOI:10.1016/j.tet.2010.02.062
日期:2010.6
control is attained by employing allenic alkoxides, where the proximal heteroatom dictates the site-selectivity in a process that proceeds by net formal metallo-[3,3] rearrangement (directed carbometalation/elimination). Stereoselectivity in these reactions is complex, with both the nature of allene substitution and relative stereochemistry of the substrate impacting the stereoselective generation of each
Gold-Catalyzed <i>N</i>,<i>O</i>-Functionalizations of 6-Allenyl-1-ynes with <i>N</i>-Hydroxyanilines To Construct Benzo[<i>b</i>]-azepin-4-one Cores
作者:Antony Sekar Kulandai Raj、Balaji S. Kale、Bhanudas Dattatray Mokar、Rai-Shung Liu
DOI:10.1021/acs.orglett.7b02629
日期:2017.10.6
Gold-catalyzedreactions of 6-allen-1-ynes with N-hydroxyanilines afford thermally stable benzoazepin-4-ones in anti-selectivity; these anti-configured products are easily isomerized to their syn-isomers on a silica column. The mechanism of reactions likely involve initial nitrone/allene cycloadditions, followed by skeletal rearrangement of resulting intermediates.
Reprint of “Allene–alkyne cross-coupling for stereoselective synthesis of substituted 1,4-dienes and cross-conjugated trienes”
作者:Heidi L. Shimp、Alissa Hare、Martin McLaughlin、Glenn C. Micalizio
DOI:10.1016/j.tet.2008.03.086
日期:2008.7
Titanium-mediated cross-coupling of allenic alcohols with alkynes has been investigated. Divergent reaction pathways were discovered that provide either stereodefined 1,4-dienes or substituted cross-conjugated trienes. In short, allene substitution plays a critical role in the determination of reaction pathway.