Intramolecular Chiral Relay at Stereogenic Nitrogen. Synthesis and Application of a New Chiral Auxiliary Derived from (1R,2S)-Norephedrine and Acetone

Cobalt-catalyzed regioselective hydrohydrazination of epoxides

Using an air-stable cobalt catalyst [Cp*Co(1,2-Ph2PC6H4S)(NCMe)]BF4 (1, Cp* = Me5C5-), we have achieved catalytic regioselective hydrohydrazination of epoxides to 1,1-hydrazinoalcohols in an atom-economical manner. The catalysis involves a cobalt-hydrazine intermediate, in which the NH2 group of the hydrazine binds to the metal center, inhibiting its nucleophilic reactivity and allowing the NH group to participate in the regioselective hydrohydrazination.

Synthesis, characterization and DNA interaction studies of new copper complex containing pseudoephedrine hydrochloride drug

A new copper(II) complex, [Cu(pse)(phen)Cl₂]; in which phen = 1,10-phenanthroline and pse = pseudoephedrine hydrochloride drug; was synthesized and characterized by FT-IR, Mass and UV-Vis spectroscopy in combination with computational methods. Binding interaction of this complex with calf thymus DNA (ct-DNA) has been investigated by absorption, emission, circular dichroism, molecular docking and viscosity measurements. The complex displays significant binding properties of ct-DNA. The results of fluorescence and UV-Vis absorption spectroscopy indicated that, this complex interacted with ct-DNA in a groove-binding mode, and the binding constant was 8 × 10⁴ L mol^-1. Competitive fluorimetric studies with Hoechst 33258 have shown that Cu(II) complex exhibit the ability to displace the DNA-bound Hoechst 33258 indicating that it binds to DNA in strong competition with Hoechst 33258 for the groove binding. Furthermore, the complex induces detectable changes in the CD spectrum of ct-DNA and does not induce any changes in DNA viscosity which verified the groove-binding mode. The molecular modeling results illustrated that the complex strongly binds to groove of DNA by relative binding energy of docked structure (-27.61 kJ mol^-1).

Direct asymmetric syntheses of chiral aldehydes and ketones via N-acyl chiral auxiliary derivatives including chiral Weinreb amide equivalents

This article covers N-acyl chiral auxiliary-based approaches to the asymmetric synthesis of enantiopure aldehydes and ketones. The use of diastereoisomerically pure N-acyl derivatives of chiral auxiliaries (including chiral Weinreb amide equivalents) and their conversion to the corresponding enantiopure aldehydes and ketones in a single synthetic operation by treatment with a hydride reducing agent or an organometallic reagent, respectively, are highlighted.

(6R)-2-tert-Butyl-6-[(4R,5S)-3-isopropyl-4-methyl-5-phenyloxazolidin-2-yl]phenol

In the title compound, C₂₃H₃₁NO₂, the lone pair on the nitro­gen atom is oriented to facilitate intra­molecular hydrogen bonding with the hydr­oxy group residing on the phenyl substituent. The five-membered ring adopts an envelope confornmation with the O atom at the flap. The absolute stereochemistry was verified by measurement of optical activity using a digital polarimeter.

(6S)-2,4-Di-tert-butyl-6-[(4S,5R)-3-isopropyl-4-methyl-5-phenyloxazolidin-2-yl]phenol

The title oxazolidine compound, C₂₇H₃₉NO₂, was synthesized from N-isopropyl­norephedrine. The dihedral angle between the aromatic rings is 70.33 (5)°. The N atom of the heterocycle is oriented to allow intra­molecular O—H⋯N hydrogen bonding with the hydr­oxy substituent.

(5R,6S)-4-Isopropyl-5-methyl-6-phenyl-3-propanoyl-2H-1,3,4-oxadiazinan-2-one

The title compound, C₁₆H₂₂N₂O₃, was synthesized during the course of a study on (1R,2S)-norephedrine-derived 1,3,4-oxadiazinan-2-ones. The conformation adopted by the isopropyl group is pseudo-axial relative to the oxadiazinan core. The allylic strain contributes to this conformational arrangement.

(5S,6R)-5-Methyl-6-phenyl-4-propyl-1,3,4-oxadiazinane-2-thione

The title molecule, C13H18N2OS, is an oxadiazinanthione derived from (1R,2S)-norephedrine. There are two molecules in the asymmetric. Both adopt roughly half-chair conformations; however, the 5-position carbon orients out of opposite faces of the oxadiazinanthiones plane in the two molecules. In the crystal structure, they are oriented as a dimer linked by a pair of N—H...S hydrogen bonds. The absolute configuration has been established from anomalous dispersion and confirms the known stereochemistry based on the synthetic procedure.

(5S,6S)-4,5-Dimethyl-3-methyl-acryloyl-6-phenyl-1,3,4-oxadiazinan-2-one

The title compound, C₁₅H₁₈N₂O₃, is an example of an oxadiazinan-2-one with significant inter­action between the N₃-acyl and N₄-methyl groups. These steric inter­actions result in a large torsion angle between the two carbonyl groups, not present with acyl substituents with less steric demand.

(4R,5S)-5-Benzyl-4-isopropyl-1,3,4-oxadiazinan-2-one

The title compound, C(13)H(18)N(2)O(2), is an N(4)-isopropyl-l-phenyl-alanine-based oxadiazinanone. Although the two mol-ecules in the asymmetric unit are oriented appropriately for hydrogen bonding, the distance between the donor and acceptor atoms is large enough to support only weak, if any, hydrogen bonding. The absolute configuration is known based on the known starting compounds in the synthetic procedure.