10.1002/anie.201708519
The research focuses on the diastereoselective synthesis of 2,5-disubstituted pyrrolidines from aliphatic azides using iron dipyrrinato complexes as catalysts. The study combines experimental and theoretical approaches to understand and enhance the diastereoselectivity of the C–H amination reaction. Reactants include 1-azido-1-aryl-hex-5-ene substrates with various electronic and steric properties, and di-tert-butyldicarbonate (Boc2O) as a reagent. The experiments involve the catalytic cyclization of these substrates to form pyrrolidines with high diastereoselectivity. The analyses used include 1H NMR, combustion analysis, single crystal X-ray diffraction, and DFT calculations to determine the reaction mechanism, optimize catalyst design, and predict the selectivity of the reaction. The research resulted in the development of an iron-phenoxide catalyst that significantly improved the diastereoselectivity of the cyclization, yielding syn 2,5-disubstituted pyrrolidines with >20:1 syn:anti diastereoselectivity.
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.
10.1002/jhet.5570320225
The research aimed to synthesize a series of N'-substituted 1,4-benzodiazepine-1-carbothioamides (2a-j) and investigate their anti-HIV activity. The researchers used a precursor, 1,4-benzodiazepine 11, and reacted it with various N-substituted isothiocyanates or sodium thiocyanate-trifluoroacetic acid to create the target compounds. Key chemicals involved in the synthesis included 2-aminobenzyl alcohol, di-tert-butyl dicarbonate, carbon tetrabromide, triphenylphosphine, L-alanine, and different isothiocyanates. Despite the structural resemblance of these molecules to the potent TIBO-type anti-HIV compound R82150, none of the synthesized compounds displayed anti-HIV activity in vitro, suggesting that the potent anti-HIV activity of TIBO derivatives requires an intact tricyclic structure.
10.1016/j.bmc.2014.05.014
The study focuses on the enzymatic preparation and resolution of cis and trans-3-amino-4-hydroxytetrahydrofurans and cis-3-amino-4-hydroxypyrrolidines, which are important heterocyclic amino alcohols found in bioactive natural products and drugs. The researchers utilized Candida antarctica lipases A and B as catalysts in hydrolytic processes to achieve high enantioselectivity for these heterocycles. The study successfully assigned the absolute configurations of the optically pure heterocycles obtained and demonstrated a convenient biocatalytic approach for preparing all isomers of these compounds. The findings have implications for the synthesis of complex molecules with potential biological activities, as well as for applications in organocatalysis and as chiral auxiliaries.
10.1039/b003789n
The research focuses on synthesizing and analyzing the conformational behavior of an eight-membered lactam dipeptide. The purpose was to study self-recognition and dimerization in cis-disubstituted medium-ring lactam dipeptides as a part of designing β-turn mimetics. The synthesis involved 12 steps starting from L-serine-derived compounds, yielding the dipeptide with a semi-extended conformation capable of head-to-tail dimerization (Kdim ~ 100 dm3/mol in CDCl2CDCl2). Conformational analyses using NMR, IR, and vapour pressure osmometry revealed strong intermolecular interactions. Chemicals used included L-serine-derived oxazolidines, dibutyltin oxide, di-tert-butyl dicarbonate, and diphenylphosphoryl azide, among others.
10.1055/s-2003-44986
The study presents a convenient protocol for the esterification of carboxylic acids with alcohols using di-t-butyl dicarbonate [(BOC)2O] as an activating agent and catalytic amounts of N,N-dimethylaminopyridine (DMAP). The reaction involves mixing stoichiometric amounts of carboxylic acids and primary or secondary alcohols, which are then treated with (BOC)2O in the presence of DMAP to produce the corresponding esters. The byproducts, t-butanol and CO2, are volatile, simplifying the purification process compared to the standard DCC/DMAP method. The study optimizes reaction conditions, such as temperature and solvent choice, and demonstrates the protocol's broad applicability with various alcohols and carboxylic acids, including those with sensitive functional groups. The method is particularly useful for preparative chemistry, combinatorial chemistry, and drug discovery due to its tolerance of a wide range of functionalities and the ease of product purification.
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