Showing papers by "Sergey Sergeyev published in 2013"
TL;DR: VCD spectroscopy itself is found to have the ability to identify diastereoisomers, and simultaneous use of these chiroptical spectroscopic methods and NMR chemical shifts aids in increasing the reliability of stereochemistry assignment of diasterenoisomers.
Abstract: The stereochemistry of all four stereoisomers of tadalafil is determined using vibrational circular dichroism (VCD), electronic circular dichroism (ECD), and optical rotatory dispersion (ORD) spectroscopy. By comparing experimentally obtained VCD spectra to computationally simulated ones, the absolute configuration of the enantiomeric pair (6R, 12aR)/(6S, 12aS) can be confidently assigned without prior knowledge of their relative stereochemistry. IR and NMR spectra are used to aid the assignment of the relative stereochemistry. The IR and VCD difference spectra further confirm the assignment of all stereoisomers. ECD and ORD spectra are used to investigate the complementarity of the three chiroptical techniques. VCD spectroscopy itself is found to have the ability to identify diastereoisomers, and simultaneous use of these chiroptical spectroscopic methods and NMR chemical shifts aids in increasing the reliability of stereochemistry assignment of diastereoisomers.
49 citations
TL;DR: An auto-tandem Pd-catalyzed process consisting of an intramolecular direct arylation and an intermolecular Buchwald-Hartwig reaction for C-ring amino-substituted 1-methyl-1H-α-carboline synthesis has been developed and reveals a rate effect of the inorganic base on the C-H activation step.
31 citations
TL;DR: In this article, the influence of free fatty acids, water, temperature, and reaction time on the catalyst-free microwave-assisted transesterification of triglycerides with 1-butanol was studied using the respon...
Abstract: The influence of the free fatty acids, water, temperature, and reaction time on the catalyst-free microwave-assisted transesterification of triglycerides with 1-butanol was studied using the respon...
5 citations
TL;DR: In this paper, a regioselective auto-tandem Pd-catalyzed process consisting of intramolecular direct arylation and a consecutive intermolecular Buchwald-Hartwig reaction is developed.
Abstract: A regioselective auto-tandem Pd-catalyzed process consisting of intramolecular direct arylation and a consecutive intermolecular Buchwald-Hartwig reaction is developed.