Synthesis of Polysubstituted Indoles and Indolines by Means of Zirconocene-Stabilized Benzyne Complexes
摘要:
The development of a new method for the regiospecific synthesis of polysubstituted indoles and indolines is reported. The key steps involve the generation of zirconocene-stabilized benzyne complexes and subsequent intramolecular olefin insertion reactions to provide tricyclic indoline zirconacycles. The zirconacyclic intermediates were cleaved with iodine to yield diiodo indolines, which were converted to a wide variety of indole and indoline products, such as analogs of tryptamine, serotonin, tryptophan, and the pharmacophore of CC-1065.
Effect of Ligand Structure on the Asymmetric Cyclization of Achiral Olefinic Organolithiums
作者:Michael J. Mealy、Matthew R. Luderer、William F. Bailey、Michael Bech Sommer
DOI:10.1021/jo049477+
日期:2004.9.1
The ability of a large and chemically diverse set of 30 chiral ligands to effect asymmetriccyclization of 2-(N,N-diallylamino)phenyllithium (1), derived from N,N-diallyl-2-bromoaniline (2) by low-temperature lithium−bromine exchange, has been investigated in an attempt to elucidate the structural motifs required to provide high enantiofacial selectivity in the ring closure. Although none of the ligands
Fast Tin-Free Hydrodehalogenation and Reductive Radical Cyclization Reactions: A New Reduction Process
作者:Santiago E. Vaillard、Al Postigo、Roberto A. Rossi
DOI:10.1021/jo035477i
日期:2004.3.1
The photostimulated reactions of several aryl and alkyl chlorides and bromides with the monoanion of reduced ethyl benzoate 5H furnish the reduced products in high yields. If the aryl moieties have suitable double bonds, the cyclized reduced products are obtained in high yields. The photostimulated reaction of 1-allyloxy-2-bromobenzene (1a) with 5H affords 3-methyl-2,3-dihydro-benzofuran (2a) in 97%
Borane Catalyzed Redox Isomerization of 2‐Amino Chalcones: Hydride Abstraction or Hydride Migration?
作者:Rundong Zhou、Jan Paradies
DOI:10.1002/ejoc.202100883
日期:2021.12.14
The borane catalyzed redox isomerization of 2-amino chalocones was developed. Mechanistic investigations by kinetic, isotopic labelling, and competition experiments as well as computational studies corroborate the concerted [1,5] hydride shift as operative mechanism. The redox isomerization products are obtained in high yield and up to >95 : 5 diastereoselectivity.
weak interactions between the ligand and the substrate. The relative efficiency of the three ligands and sense of stereoinduction for the most efficient diether and amino ether ligands prove to be foreseeable by modeling the reaction with the parent achiral 1,2-bidentate additives and comparing the diastereomeric transition states stemming from the two half-chair conformations of their lithium chelate
A new class of chiral 1,2-amino ether ligands, readily accessible from naturally occurring alpha-amino- or alpha-hydroxy acids, was found to provide high levels of both conversion and stereocontrol (up to 95:5 er) in intramolecular carbolithiation reactions, outperforming the benchmark ligand (-)-sparteine. The ligand could, be used in a substoichiometric amount (0.25 equiv) without significant loss of enantios electivity.