Preparation of <i>N</i>-Alkyl 2-Pyridones via a Lithium Iodide Promoted <i>O</i>- to <i>N</i>-Alkyl Migration: Scope and Mechanism
作者:Sarah Z. Tasker、Michael A. Bosscher、Christina A. Shandro、Erica L. Lanni、Keun Ah Ryu、Gregory S. Snapper、Jarrad M. Utter、Bruce A. Ellsworth、Carolyn E. Anderson
DOI:10.1021/jo3015424
日期:2012.9.21
An efficient and inexpensive LiI-promoted O- to N-alkyl migration of 2-benzyloxy-, 2-allyloxy-, and 2-propargyloxypyridines and heterocycles is reported. The reaction produces the corresponding N-alkyl 2-pyridones and analogues under green, solvent-free conditions in good to excellent yields (30 examples, 20–97% yield). This method has been shown to be intermolecular and requires heat and lithium cation
Synthesis of a New Class of β-Iodo <i>N</i>-Alkenyl 2-Pyridones
作者:Sarah Z. Tasker、Benjamin M. Brandsen、Keun Ah Ryu、Gregory S. Snapper、Richard J. Staples、Roger L. DeKock、Carolyn E. Anderson
DOI:10.1021/ol202679t
日期:2011.12.2
from substituted 2-propargyloxypyridines has been discovered . These compounds present a unique complement of orthogonal functionality and structural characteristics that are unavailable via other routes. The ready access to these compounds renders them an important entry point for the preparation of more complex N-alkyl pyridone-containing targets.
Aluminium trichloride catalyses the expeditious direct conversion of tetrahydropyranylethers to silyl ethers. This one-step transformation is chemoselective versus deprotection of the acetal and hydrosilylation of unsaturated carbon–carbon bonds, and can also be applied to linear acetals. A possible mechanism is tentatively proposed.
A Brønsted‐acid‐catalyzed intramolecular enantioselective SN2′ reaction was developed utilizing trichloroacetimidate as a leavinggroup. The findings indicated that dual activation of the substrates is operative. This metal‐free allylic alkylation allows highly enantioselective access to 2‐vinylpyrrolidines bearing various substituents.
利用三氯乙酰亚氨酸酯作为离去基团开发了布朗斯台德酸催化的分子内对映选择性S N 2'反应。该发现表明底物的双重激活是有效的。这种无金属的烯丙基烷基化作用使对带有各种取代基的2-乙烯基吡咯烷酮具有高度对映选择性。
Cobalt-Catalyzed Cross Addition of Silylacetylenes to Internal Alkynes
A CoCl2·6H2O/Zn reagent using 2-(2,6-diisopropylphenyl)iminomethylpyridine (dipimp), 1,2-bis(diphenylphosphino)ethane (dppe), or 1,2-bis(diphenylphosphino)benzene (dppPh) as a ligand effectively catalyzed the cross-addition reaction of silylacetylene to internal alkynes. The reaction of some unsymmetrical internal alkynes, such as 3-arylpropargyl alcohols, proceeded in a highly regioselective manner
使用2-(2,6-二异丙基苯基)亚氨基甲基吡啶(dipimp),1,2-双(二苯基膦基)乙烷(dppe)或1,2-双(二苯基膦基)苯(dppPh)的CoCl 2 ·6H 2 O / Zn试剂)作为配体有效地催化了甲硅烷基乙炔与内部炔烃的交叉加成反应。一些不对称内部炔烃(例如3-芳基炔丙醇)的反应在dppe或dppPh的存在下以高度区域选择性的方式进行,但在dipimp的存在下产生了近1:1的区域异构体混合物。使用1-氘代2-甲硅烷基乙炔的反应结果表明,该反应涉及甲硅烷基乙炔C–H键与钴的直接氧化加成。