3 research outputs found
Synthesis of Lactams by Isomerization of Oxindoles Substituted at Cā3 by an ĻāAmino Chain
Oxindoles
substituted at N-1 by electron-withdrawing groups and
at C-3 by Ļ-amino chains of various lengths undergo mild and
easy isomerization to new 5- to 12-membered lactams in good yields
(30ā96%). As efficient asymmetric syntheses of diversely 3,3-disubstituted
oxindoles are currently developed, this isomerization provides a new
and valuable access to medium-sized lactams Ī±-substituted with
a quaternary asymmetric carbon bearing a 2-aminophenyl residue
Synthesis of Lactams by Isomerization of Oxindoles Substituted at Cā3 by an ĻāAmino Chain
Oxindoles
substituted at N-1 by electron-withdrawing groups and
at C-3 by Ļ-amino chains of various lengths undergo mild and
easy isomerization to new 5- to 12-membered lactams in good yields
(30ā96%). As efficient asymmetric syntheses of diversely 3,3-disubstituted
oxindoles are currently developed, this isomerization provides a new
and valuable access to medium-sized lactams Ī±-substituted with
a quaternary asymmetric carbon bearing a 2-aminophenyl residue
Variable Magnetic Interactions between S = 1/2 Cation Radical Salts of Functionalizable Electron-Rich Dithiolene and Diselenolene Cp<sub>2</sub>Mo Complexes
A series of Cp<sub>2</sub>MoĀ(dithiolene) and Cp<sub>2</sub>MoĀ(diselenolene) complexes containing N-alkyl-1,3-thiazoline-2-thione-4,5-dithiolate
ligand (R-thiazdt, R = Me, Et, CH<sub>2</sub>CH<sub>2</sub>OH) and
N-alkyl-1,3-thiazoline-2-thione-4,5-diselenolate ligand (R-thiazds,
R = Me, Et) have been synthesized. These heteroleptic molybdenum complexes
have been characterized by electrochemistry, spectroelectrochemistry,
and single crystal X-ray diffraction. They act as very good electron
donor complexes with a first oxidation potential 200 mV lower than
in the prototypical Cp<sub>2</sub>MoĀ(dmit) complex and exhibit almost
planar MoS<sub>2</sub>C<sub>2</sub> (or MoSe<sub>2</sub>C<sub>2</sub>) metallacycles. All five complexes formed charge transfer salts
with a weak (TCNQ) and a strong acceptor (TCNQF<sub>4</sub>), affording
ten different charge-transfer salts, all with 1:1 stoichiometry. Crystal
structure determinations show that the S/Se substitution in the metallacycle
systematically affords isostructural salts, while the Cp<sub>2</sub>MoĀ(R-thiazdt) complexes with R equals ethyl or CH<sub>2</sub>CH<sub>2</sub>OH can adopt different structures, depending on the involvement
of the hydroxyl group into intra- or intermolecular hydrogen bonding
interactions. Magnetic susceptibility data of the salts are correlated
with their structural organization, demonstrating that a face-to-face
organization of the Me-thiazdt (or Me-thiazds) ligand favors a strong
antiferromagnetic interaction, while the bulkier R = Et or R = CH<sub>2</sub>CH<sub>2</sub>OH substituents can completely suppress such
intermolecular interactions, with the added contribution of hydrogen
bonding to the solid state organization