Ann L. Bingham

Over one hundred solvates of sulfathiazole

The sulfadrug sulfathiazole forms an extensive family of solvates and adducts, the crystal structures of which show a large variety of hydrogen-bonded frameworks.

Polymorph VI of sulfapyridine: interpenetrating two- and three-dimensional hydrogen-bonded nets formed from two tautomeric forms.

Polymorph VI of 4-amino-N-(2-pyridyl)benzenesulfonamide, C(11)H(11)N(3)O(2)S, is monoclinic (space group P2(1)/n). The asymmetric unit contains two different tautomeric forms. The structure displays N-H...N and N-H...O hydrogen bonding. The two independent molecules form two separate two- and three-dimensional hydrogen-bonded networks which interpenetrate. The observed patterns of hydrogen bonding are analogous to those in polymorph I of sulfathiazole.

Synthesis of a series of 2,3-disubstituted 4H-1,4-benzothiazines and X-ray crystal structure of ethyl 7-chloro-3-methyl-4H-1,4-benzothiazine-2-carboxylate

The reaction between 2-aminobenzenethiol and ethyl acetoacetate is studied under a variety of conditions, and a procedure for the exclusive synthesis of 1,4-benzothiazines by the neat reaction of substituted aminothiols with β-ketoesters and β-dicarbonyl compounds in 85–96% yield is described. With microwave heating, even when both the reactants are solid, yields are high, reaction times brief, and work-up easy. A facile reaction is also observed even in a solid-state reaction. The molecular structure of ethyl 7-chloro-3-methyl-4H-1,4-benzothiazine-2-carboxylate (4d) was determined by single-crystal X-ray diffraction.

Stereochemically non-rigid transition metal complexes of 2,6-bis(phenyliminomethyl)pyridine and derivatives. Crystal structure of fac-[ReBr(CO)3(PMTFA)] (PMTFA=2,6-pyridylene-bis-(methylene-2-trifluoromethylaniline)

Abstract The Schiff bases 2,6-bis(phenyliminomethyl)pyridine and its derivatives (L) form bidentate chelate complexes with transition metals Re I , Pt IV and Pd II of general formulation fac -[ReBr(CO) 3 L], fac -[PtXMe 3 L] (X=Cl, Br or I), and cis -[Pd( p -CF 3 C 6 F 4 ) 2 L]. In solution these complexes are stereochemically non-rigid, undergoing 1,4-metallotropic shifts and restricted rotations of the substituted aromatic rings attached to the metal-coordinated imino nitrogen. Rates and activation energies of these internal motions were measured by one-dimensional NMR bandshape analysis and two-dimensional EXSY NMR experiments over a range of solution temperatures. Free energy values, Δ G ‡ (298.15 K), for the fluxional shifts were in the range 76–97 kJ mol −1 with the Pd II complexes having the lowest energies. An X-ray crystal structure of fac -[ReBr(CO) 3 PMTFA] (PMTFA=2,6-pyridylene-bis(methylene-2-trifluoroaniline)) showed the pendant imine function to be in an E -conformation with its nitrogen trans to the pyridyl nitrogen.

Reaction of β‐Lapachone with 1,2‐Diamines: Facile Synthesis of Novel Tetracyclic Pyrazines

Abstract The reactions of β‐lapachone (1) with 1,2‐diaminoethane (2) and 1,2‐diaminopropane (4) gave the tetracyclic pyrazine derivatives (3) and mixtures of (5) and (6), respectively, while reaction with o‐phenylene diamine (7) gave the quinoxaline derivative (8). The structure of pyrazine derivative (3) is confirmed by single‐crystal X‐ray diffraction study.

Regioselective synthesis of 4'-amino-1'H-spiro [cyclohexane-1,2' (pyrimido [1,2 -a ]benzimidazole ) ]-3'-carbonitrile in aqueous medium

A simple, mild and environment-friendly procedure for synthesis of 4′-amino-1′H-spiro[cyclohexane-1,2′-(pyrimido[1,2-a]benzimidazole)]-3′-carbonitrile is developed using microwave irradiation in water. The product is obtained in short time, in excellent yield, and in a good state of purity. The reaction pathway and the influence of reaction conditions on regiochemistry are also investigated. The regioselectivity in this process is confirmed chemically and by single-crystal X-ray molecular structure determination.