10.1016/j.tetasy.2009.12.002
The research focuses on the synthesis of 4,4'-biquinazoline alcohols, which are chiral catalysts used in the enantioselective alkynylation of aldehydes with phenyl acetylene. The study outlines a series of chemical reactions beginning with the condensation of (S)-2-acetoxycarboxylic acid chlorides and 2-aminobenzamide, followed by key steps such as chlorination, nickel(0)-mediated homocoupling, and deprotection to yield the desired chiral 4,4'-biquinazoline alcohols. These catalysts are then combined with Ti(OiPr)4 and utilized in the asymmetric addition of zinc acetylide, generated in situ from phenylacetylene and diethylzinc, to aldehydes. The experiments involved various reactants, including SOCl2, anthranilamide, NaOH, TBDMSCl, POCl3, PhNEt2, NiCl2?6H2O, Zn, DMF, and Bu4NF, among others. The analyses used to characterize the compounds and determine their enantiomeric purities included HPLC, NMR spectroscopy, IR spectroscopy, X-ray diffraction, and specific rotation measurements. The best enantiomeric excess achieved in this study was 75%.
10.1016/S0968-0896(01)00191-2
The research focuses on the optimization of multidrug resistance (MDR) modulators, specifically targeting the synthesis and study of ring-substituted derivatives of two known MDR inhibitors. The aim was to enhance their activity and selectivity in reversing MDR in cancer treatment while minimizing side effects. The study involved the synthesis of various compounds through reactions with different substituted fluorenone derivatives and 5-amino-2-(3,4-dimethoxyphenyl)-2-(methylethyl)pentanenitrile, using reagents like titanium (IV) isopropoxide and sodium cyanoborohydride. The synthesized compounds were then evaluated for their MDR-modulating activity and cardiovascular effects. The experiments included assessing the compounds' ability to revert MDR in anthracycline-resistant K562 cells through spectrofluorometric monitoring of pirarubicin uptake, as well as testing their inotropic, chronotropic, and vasodilator activities on guinea pig isolated atria and aortic strip preparations. The analyses encompassed determining the compounds' chemical and physical characteristics, infrared and 1H NMR spectral data, and pharmacological properties such as potency, efficacy, and affinity for P-glycoprotein.
10.1016/S0040-4020(01)97596-9
The research focuses on the total synthesis of L-hexoses, which are enantiomerically pure polyhydroxylated natural products. The purpose of this study was to demonstrate the power of the "reagent-control" strategy in organic chemistry, which utilizes powerful asymmetric reagents and catalysts to construct any stereochemical combination, including those that are difficult to make using traditional "substrate-control" methods. The researchers employed a reiterative two-carbon extension cycle consisting of four key transformations: conversion of an aldehyde to an allylic alcohol, asymmetric epoxidation, regioselective opening of the epoxy alcohol, and oxidation to generate a bis-homologated aldehyde. Chemicals used in the process include aldehydes, allylic alcohols, L-(+)-diisopropyl tartrate, titanium tetraisopropoxide, t-butylhydroperoxide, benzenethiol, and various Wittig reagents for olefination, among others. The conclusions of the research confirmed the efficiency and generality of the reagent-control methodology in the total synthesis of all eight L-hexoses, showcasing its potential for selective construction of any one of the sixteen hexose stereoisomers.
10.1016/j.tet.2008.03.086
The research focuses on the titanium-mediated cross-coupling of allenic alcohols with alkynes to achieve the stereoselective synthesis of substituted 1,4-dienes and cross-conjugated trienes. The study reveals that the substitution on allenes significantly influences the reaction pathway, allowing for the selective formation of either 1,4-dienes or cross-conjugated trienes. Key chemicals used in the process include titanium(IV) isopropoxide (Ti(Oi-Pr)4), ClTi(Oi-Pr)3, c-C5H9MgCl, and various allenic alcohols and alkynes. The findings demonstrate that this method provides a highly regio- and stereoselective approach to synthesize complex molecular structures, highlighting its potential utility in the synthesis of complex polycyclic systems.
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