21378-21-2Relevant articles and documents
Synthetic studies of kinamycin antibiotics: Stereoselective synthesis of the highly oxygenated D-ring and construction of the ABD-ring system of kinamycins
Ouzouni, Maria-Dimitra,Fokas, Demosthenes
, p. 6181 - 6189 (2013)
A concise and stereoselective synthesis of the highly oxygenated D-ring of the kinamycin family of antitumor antibiotics was achieved from commercially available 3-methyl-2-cyclohexen-1-one. The key steps included a regioselective isomerization of a cis-epoxy alcohol, a regioselective reductive ring opening of a benzylidene ketal, and a stereoselective α-hydroxy-directed ketone reduction. The Ullmann coupling between a bromonaphthaldehyde AB-ring fragment and an α-iodocyclohexenone, which is a versatile D-ring precursor, effected the construction of the functionalized ABD-ring system that may provide access to kinamycin F and its structural analogues. A concise and stereoselective synthesis of the highly oxygenated D-ring of the kinamycins was achieved from commercially available 3-methyl-2-cyclohexenone. Also, a metal-catalyzed coupling reaction between an AB-ring fragment and a D-ring precursor enabled the construction of the functionalized ABD-ring system that may provide entry to synthesis of the kinamycins.
Liquid-phase oxidation of olefins with rare hydronium ion salt of dinuclear dioxido-vanadium(V) complexes and comparative catalytic studies with analogous copper complexes
Maurya, Abhishek,Haldar, Chanchal
, (2021/02/26)
Homogeneous liquid-phase oxidation of a number of aromatic and aliphatic olefins was examined using dinuclear anionic vanadium dioxido complexes [(VO2)2(salLH)]? (1) and [(VO2)2(NsalLH)]? (2) and dinuclear copper complexes [(CuCl)2(salLH)]? (3) and [(CuCl)2(NsalLH)]? (4) (reaction of carbohydrazide with salicylaldehyde and 4-diethylamino salicylaldehyde afforded Schiff-base ligands [salLH4] and [NsalLH4], respectively). Anionic vanadium and copper complexes 1, 2, 3, and 4 were isolated in the form of their hydronium ion salt, which is rare. The molecular structure of the hydronium ion salt of anionic dinuclear vanadium dioxido complex [(VO2)2(salLH)]? (1) was established through single-crystal X-ray analysis. The chemical and structural properties were studied using Fourier transform infrared (FT-IR), ultraviolet–visible (UV–Vis), 1H and 13C nuclear magnetic resonance (NMR), electrospray ionization mass spectrometry (ESI-MS), electron paramagnetic resonance (EPR) spectroscopy, and thermogravimetric analysis (TGA). In the presence of hydrogen peroxide, both dinuclear vanadium dioxido complexes were applied for the oxidation of a series of aromatic and aliphatic alkenes. High catalytic activity and efficiency were achieved using catalysts 1 and 2 in the oxidation of olefins. Alkenes with electron-donating groups make the oxidation processes easy. Thus, in general, aromatic olefins show better substrate conversion in comparison to the aliphatic olefins. Under optimized reaction conditions, both copper catalysts 3 and 4 fail to compete with the activity shown by their vanadium counterparts. Irrespective of olefins, metal (vanadium or copper) complexes of the ligand [salLH4] (I) show better substrate conversion(%) compared with the metal complexes of the ligand [NsalLH4] (II).
Straightforward chemo- and stereoselective fluorocyclopropanation of allylic alcohols: Exploiting the electrophilic nature of the not so elusive fluoroiodomethyllithium
Colella, Marco,Tota, Arianna,Gro?johann, Angela,Carlucci, Claudia,Aramini, Andrea,Sheikh, Nadeem S.,Degennaro, Leonardo,Luisi, Renzo
supporting information, p. 8430 - 8433 (2019/07/22)
An unprecedented direct fluorocyclopropanation of allylic alcohols is reported. This simple method involves the not so elusive fluoroiodomethyllithium, a carbenoidic intermediate that under the developed conditions discloses its electrophilic nature. Gratifyingly, the reaction turned out to be highly chemo- and stereoselective, and DFT calculations provided insights into the structure and nature of this new type of carbenoid.
