Application of iridium catalyzed allylic substitution reactions in the synthesis of branched tryptamines and homologues via tandem hydroformylation–Fischer indole synthesis
作者:Bojan P. Bondzic、Andreas Farwick、Jens Liebich、Peter Eilbracht
DOI:10.1039/b809143a
日期:——
reactions with a tandem hydroformylation-Fischer indole synthesis sequence as a highly diversity-oriented strategy for the synthesis of tryptamines and homologues was explored. This modular approach allows the substituents at C3 of the indole core, the type of the amine moiety, and the distance of the amine moiety to the indole core in the final synthetic step to be defined. The starting materials required
Mechanistic Studies on Pd-Catalyzed Telomerization and Co-Cyclization of Butadiene: Amphiphilicity of Bis-π-allylpalladium Intermediate in the Presence of Phosphine Ligand
Pd-catalyzed reactions of butadiene, which proceed through a bis-π-allylpalladium intermediate, (η3,η3-C8H12)Pd (2), were performed in the presence of both a pronucleophile (aceto- or cyanoacetate) and an electrophile (benzaldehyde). Methyl aceto- or cyanoacetate and benzaldehyde reacted independently with 2 to give telomers 8 and the divinyl-substituted pyranes 9, respectively. In the case of methyl cyanoacetate, the co-cyclization of 2 with 2-cyano-3-phenylpropenoate (11) formed in situ also took place to afford the cyclohexane derivative 10. Namely, three kinds of amphiphilic additions of the C8-chain of 2 occurred to δ+H–Nuδ−, δ+C=Cδ−, and δ+C=Oδ− simultaneously in a one-pot reaction. The Pd-catalyzed reaction of allyl chloride, allyltributylstannane, methyl cyanoacetate, and benzaldehyde was undertaken under neutral conditions, expecting the amphiphilic reactions by the intermediacy of (η3-C3H5)2Pd (6) formed in situ. Allylation of both benzaldehyde and methyl cyanoacetate took place. Competitively amphiphilic bis-allylation of the polar double bond of 11 also occurred to form the 1,7-octadiene derivative 18. The mechanisms of both reactions can be explainable in terms of the amphiphilicity of the intermediates (2 and 6) in the presence of a phosphine ligand.
Unconventional Reactivity of a Grubbs Catalyst: Hydroalkylation Overriding Metathesis
作者:Amit Singh Adhikari、Nilanjana Majumdar
DOI:10.1021/acs.orglett.3c03456
日期:2023.12.8
Unprecedented reactivity of a Grubbscatalyst has been disclosed in a reaction between vinyl azaarenes and alkenylnitriles under standard metathesis conditions. No metathesis was observed; only hydroalkylation products were obtained in high yields. The practical utility of this method has been demonstrated by the application of the products in useful transformations, e.g., the formation of cyclic iminoesters
Halogen-Bonding-Enabled Photoinduced Atom Transfer Radical Addition/Cyclization Reaction Leading to Tricyclic Heterocycles
作者:Eiji Yamaguchi、Masanobu Murai、Akichika Itoh
DOI:10.1021/acs.joc.4c00204
日期:2024.5.3
Atomtransferradicaladdition (ATRA) reactions are crucial for the dual functionalization of unsaturated hydrocarbons. Radical generation, pivotal in ATRA, has seen advancements from thermal to photochemical methods. Recent focus on halogen-bonding-based radical generation, including our group’s innovative photochemical approach, offers cost-effective alternatives to transition-metal-dependent photocatalysts