10.1016/S0040-4020(97)00377-3
The study presents an enantioselective synthetic route to trans-2,6-disubstituted piperidines, focusing on the synthesis of (S)-2-methyl tetrahydropyridine-N-oxide, a key intermediate. This compound is crucial for constructing trans-2,6-disubstituted piperidines via a [3+2] nitrone cycloaddition reaction. The research demonstrates the utility of this method by synthesizing the fire ant venom alkaloid, (+)-solenopsin-A, through a series of steps including nitrone formation, cycloaddition, and reductive cleavage. The methodology is highlighted for its potential application in synthesizing similar piperidine-based alkaloids, with implications for pharmaceuticals, such as treatments for Alzheimer's disease.
10.1246/bcsj.62.2093
The research focused on the rotational isomerism in fluorene derivatives, specifically examining the conformational equilibria of 9-substituted 9-(2-bromomethylphenyl)fluorene derivatives. The purpose of the study was to understand the conformational equilibria (ap-sp) of these compounds based on the kinetic data for internal rotation obtained through HNMR spectroscopy. The researchers synthesized eight 9-substituted 9-(2'-bromomethylphenyl)fluorene derivatives and compared their HNMR behavior with those of 9-substituted 9-(2'-methylphenyl)fluorene derivatives. The conclusions drawn from the study indicated that the conformational equilibria were influenced by electronic repulsion and/or steric hindrance between the 2'-bromomethyl group and the 9-carbonyl group or the fluorene ring. Chemicals used in the process included NBS (N-Bromosuccinimide), BPO (Benzoyl peroxide), carbon tetrachloride, dry hydrogen bromide, and various solvents such as CDCl3, DMSO-d6, acetone-d6, and methanol-d4 for NMR spectroscopy, as well as reagents for the synthesis and purification of the fluorene derivatives.
10.1002/jhet.5570380125
The research investigates the reactions of various heterocycles with N-bromosuccinimide (NBS) in the presence or absence of water to achieve side chain versus ring bromination, aiming to synthesize important brominated heterocyclic synthons. The study explores different conditions, such as using perchloric acid, which leads to the exclusive formation of a new dibromo aminopicoline (1f) not obtained by other methods. The presence of water droplets in the reaction accelerates the rate of bromination for most heterocyclic compounds, potentially by increasing solvent polarity and maintaining a more uniform distribution of free radicals. The protecting groups on the heterocycles, such as acetyl or 4-nitrobenzoyl, also influence the ratio of side chain versus ring bromination. NBS, benzoyl peroxide, perchloric acid, and acetonitrile are key chemicals in this research, playing crucial roles in the bromination process and the formation of specific products.
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