164 research outputs found
Polymorphic form II of 4,4′-methylenebis(benzenesulfonamide)
In the title compound, C13H14N2O4S2 (alternative names: diphenylmethane-4,4′-disulfonamide, nirexon, CRN: 535–66-0), the two benzene rings form a dihedral angle of 70.8 (1)°. There are two sets of shorter (H⋯O < 2.1 Å) and longer (H⋯O > 2.4 Å) N—H⋯O hydrogen bonds per sulfonamide NH2 group, which together result in hydrogen-bonded sheets parallel (102). Adjacent sheets are connected to one another by an additional N—H⋯N interaction so that a three-dimensional network of hydrogen-bonded molecules is formed. The investigated polymorph is identical with the form II previously described by Kuhnert-Brandstätter & Moser [(1981). Mikrochim. Acta, 75, 421–440]
Reversible temperature-induced polymorphic phase transitions of [Y(OAr)<sub>3</sub>] and [Ce(OAr)<sub>3</sub>] (Ar=2,6-<sup>T</sup>Bu<sub>2</sub>-4-MeC<sub>6</sub>H<sub>2</sub>): Interconversions between pyramidal and planar geometries
Aminophobanes:hydrolytic stability, tautomerism and application in Cr-catalysed ethene oligomerisation
The bicyclic aminophobanes have significantly different chemistry from their acyclic analogues Cy2PNHR′.</p
Gliquidone
The title compound {systematic name: N-cyclohexylcarbamoyl-4-[2-(7-methoxy-4,4-dimethyl-1,3-dioxo-1,2,3,4-tetrahydroisoquinolin-2-yl)ethyl]benzenesulfonamide}, C27H33N3O6S, displays an intramolecular N—H⋯O=S interaction, as well as intermolecular N—H⋯O=C hydrogen bonds. The latter interactions lead to the formation of hydrogen-bonded chains parallel to the c axis. The conformation of the sulfonylurea fragment is in agreement with a recent theoretical study [Kasetti et al. (2010 ▶). J. Phys. Chem. B, 114, 11603–11610]
Benzylsulfamide
The crystal of the title compound [systematic name: 4-(benzylamino)benzenesulfonamide], C13H14N2O2S, displays a hydrogen-bonded framework structure. Molecules are doubly N—H⋯O hydrogen bonded to one another via their NH2 groups and sulfonyl O atoms. These interactions generate a hydrogen-bonded ladder structure parallel to the a axis, which contains fused R
2
2(8) rings. The NH group serves as the hydrogen-bond donor for a second set of intermolecular N—H⋯O=S interactions
Polythiazide
The crystal structure of the title compound, C11H13ClF3N3O4S3 (systematic name: 6-chloro-2-methyl-3-{[(2,2,2-trifluoroethyl)sulfanyl]methyl}-3,4-dihydro-2H-1,2,4-benzothiadiazine-7-sulfonamide 1,1-dioxide; CRN: 346–18–9), exhibits a two-dimensional network of hydrogen-bonded molecules parallel to (01). The NH and NH2 groups act as donor sites and the sulfonyl O atoms as acceptor sites in N—H⋯O hydrogen bonds, and a C—H⋯O interaction also occurs. The thiadiazine ring adopts an envelope conformation with the N atom bonded to sulfur at the tip of the flap, and the methyl substituent is in an axial position
B-Methylated Amine-Boranes:Substituent Redistribution, Catalytic Dehydrogenation, and Facile Metal-Free Hydrogen Transfer Reactions
Although
the dehydrogenation chemistry of amine-boranes substituted at nitrogen
has attracted considerable attention, much less is known about the
reactivity of their B-substituted analogues. When the B-methylated
amine-borane adducts, RR′NH·BH<sub>2</sub>Me (<b>1a</b>: R = R′ = H; <b>1b</b>: R = Me, R′ = H; <b>1c</b>: R = R′ = Me; <b>1d</b>: R = R′ = <i>i</i>Pr), were heated to 70 °C in solution (THF or toluene),
redistribution reactions were observed involving the apparent scrambling
of the methyl and hydrogen substituents on boron to afford a mixture
of the species RR′NH·BH<sub>3–<i>x</i></sub>Me<sub><i>x</i></sub> (<i>x</i> = 0–3).
These reactions were postulated to arise via amine-borane dissociation
followed by the reversible formation of diborane intermediates and
adduct reformation. Dehydrocoupling of <b>1a</b>–<b>1d</b> with Rh(I), Ir(III), and Ni(0) precatalysts in THF at 20
°C resulted in an array of products, including aminoborane RR′NBHMe,
cyclic diborazane [RR′N–BHMe]<sub>2</sub>, and borazine
[RN–BMe]<sub>3</sub> based on analysis by in situ <sup>11</sup>B NMR spectroscopy, with peak assignments further supported by density
functional theory (DFT) calculations. Significantly, very rapid, metal-free
hydrogen transfer between <b>1a</b> and the monomeric aminoborane, <i>i</i>Pr<sub>2</sub>NBH<sub>2</sub>, to yield <i>i</i>Pr<sub>2</sub>NH·BH<sub>3</sub> (together with dehydrogenation
products derived from <b>1a</b>) was complete within only 10
min at 20 °C in THF, substantially faster than for the N-substituted
analogue MeNH<sub>2</sub>·BH<sub>3</sub>. DFT calculations revealed
that the hydrogen transfer proceeded via a concerted mechanism through
a cyclic six-membered transition state analogous to that previously
reported for the reaction of the <i>N</i>-dimethyl species
Me<sub>2</sub>NH·BH<sub>3</sub> and <i>i</i>Pr<sub>2</sub>NBH<sub>2</sub>. However, as a result of the presence
of an electron donating methyl substituent on boron rather than on
nitrogen, the process was more thermodynamically favorable and the
activation energy barrier was reduced
Practical and Highly Selective Sulfur Ylide-Mediated Asymmetric Epoxidations and Aziridinations Using a Cheap and Readily Available Chiral Sulfide: Extensive Studies To Map Out Scope, Limitations, and Rationalization of Diastereo- and Enantioselectivities
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