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.
10.1016/j.tetlet.2011.07.035
The research presents a stereoselective synthesis of the naturally occurring pyrrolidine alkaloid, (+)-radicamine B, which possesses significant biological properties. The synthesis involves 13 steps, starting from commercially available p-hydroxybenzaldehyde, with an overall yield of 9.75%. Key reactions include Sharpless asymmetric epoxidation and Horner–Wadsworth–Emmons (HWE) olefination. Reactants used throughout the synthesis include p-hydroxybenzaldehyde, tosyl chloride, (+)-DET, NaN3, PPh3, Boc anhydride, benzaldehyde dimethylacetal, DIBAL-H, IBX, (OEt)2PO(CH2COOEt), and (+)-DIPT, among others. Analytical techniques employed to characterize the intermediates and final product included 1H NMR, 13C NMR, Mass spectrometry, and IR spectroscopy, with enantioselectivity determined by chiral HPLC. The study also discusses the biological significance of radicamine B and the challenges in its asymmetric synthesis, highlighting the efficiency and linearity of their developed synthetic protocol.
10.1055/s-0031-1289746
The research focuses on a divergent synthetic strategy based on the regioselective reductive ring-opening of a cyclic 1,2-p-methoxybenzylidene acetal. The study employs a common intermediate, (1S)-N,N-dibenzyl-1-[(4R)-2-(4-methoxyphenyl)-1,3-dioxolan-4-yl]ethanamine, synthesized in five steps from an α-bromo-α'-(R)-sulfinyl ketone, to produce p-methoxybenzyl-protected primary and secondary alcohols. These alcohols serve as precursors for the synthesis of a fully protected syn-3-amino-2-hydroxybutanoic acid and an N-benzyl 2-hydroxymethylaziridine. Key reactants include α-bromo-α'-(R)-sulfinyl ketones, diisobutylaluminum hydride, p-anisaldehyde, and various other reagents used in the synthesis and purification processes. The research involves a series of chemical reactions, such as Pummerer rearrangement, reduction with lithium aluminum hydride, and reductive cleavage using diisobutylaluminum hydride. Analytical techniques used to characterize the compounds include NMR spectroscopy, high-resolution mass spectrometry (HRMS), and optical rotation measurements. The experiments demonstrate a regioselective approach to synthesize the desired alcohols and further transform them into the target molecules, showcasing the synthetic potential of the methodology for creating biologically important molecules.
10.1016/S0968-0896(01)00012-8
The research focuses on the synthesis and evaluation of octahydro- and decahydrobenzo[c]quinolizin-3-one derivatives as selective inhibitors of human steroid 5α-reductase type I (5αR-1). The study involved the preparation of these compounds through sequential rearrangement-annulation of isoxazolines, followed by Mannich-Michael tandem reactions. DIBAL-H (diisobutylaluminum hydride), used for selective reduction of ester groups. The inhibitory potency of the synthesized compounds was assessed using CHO cells expressing 5αR-1 and 5αR-2, with IC50 values determined to evaluate their effectiveness. Key reactants included Danishefsky's diene, N-Boc iminium ions, and various Lewis acids, while analytical techniques such as NMR, mass spectrometry, and IR spectroscopy were employed to characterize the synthesized compounds and confirm their structures.
10.1002/ejoc.200901230
The research investigates the use of diisobutylaluminium hydride (DIBAL-H) to promote secondary rim regioselective bis-de-O-methylation of permethylated β-cyclodextrin, resulting in products like diol 5, tetrol 6, and hexol 7. The study explores the mechanism behind this reaction, contrasting it with the selective bis-de-O-benzylation of perbenzylated cyclodextrins. Key chemicals involved include permethylated β-cyclodextrin (4), DIBAL-H, and various intermediates and products such as 2A,3B-dihydroxy-per-O-methyl-β-cyclodextrin (5), 2A,3B,2E,3D-tetrahydroxy-per-O-methyl-β-cyclodextrin (6), and 2A,3B,2E,3D,2F,3G-hexahydroxy-per-O-methyl-β-cyclodextrin (7). The research also involves the synthesis of alcohols 8 and 13 to study their reactivity towards DIBAL-H, providing insights into the stepwise mechanism of the demethylation process.
10.1021/ja2010829
The research focuses on the development of a catalytic enantioselective method for the synthesis of alkyne-substituted all-carbon quaternary stereogenic centers. The experiments involve the addition of alkynylaluminum reagents to variously substituted allylic phosphates, facilitated by NHC-Cu complexes derived from air-stable CuCl2·2H2O. The Al-based reagents are prepared by treating terminal alkynes with diisobutylaluminum hydride in the presence of Et3N. The reactions yield 1,4-enynes with high enantioselectivity (up to >99:1 enantiomeric ratio) and good yields (up to 98%). The study also demonstrates the utility of these enantiomerically enriched products in chemical synthesis through Au-catalyzed cyclizations. Analytical techniques such as 1H NMR, HPLC, and X-ray crystallography were used to characterize the products and assess the enantiomeric ratios and yields.
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