Reactions of anthranilamide with isocyanates: A new facile synthesis of 2,3-dihydro-5H-oxazolo[2,3-b]quinazolin-5-one and 3,4-dihydro-2H,6H-[1,3]oxazino[2,3-b]quinazolin-6-one [1]

2,3-Dihydro-5H-oxazolo[2,3-b]quinazolin-5-one 5a was synthesized from anthranilamide 1 and 2-chloro-ethyl isocyanate either by a direct reflux in methanol, or by stirring at room temperature in acetonitrile leading to the intermediate, 2-(2-chloroethyl ureido)benzamide 6a which was subsequently cyclized on heating with an organic base. However, when compound 6a was refluxed with concentrated hydrochloric acid, it furnished 3-(2-chloroethyl)-2,4-dioxo-1H,3H-quinazoline 2a in good yields. 3,4-Dihydro-2H,6.H-[1,3]-oxazino[2,3-b]quinazolin-6-one 5b , 3-(3-chloropropyl)-2,4-dioxo-1H,3.H-quinazoline 2b and 2-(3-chloropropyl ureido)benzamide 6b were obtained similarly from 1 and 3-chloropropyl isocyanate.     

Chemical Transformations of 4,6-Dimethyl-2β-hydroxy-8-oxo-3,5,7-trioxatetracyclo[7.2.1.04,11.06,10]dodecane

Reactions of 4,6-dimethyl-2β-hydroxy-8-oxo-3,5,7-trioxatetracyclo-[7.2.1.0.^4,11.0^6,10]dodecane 1 with nucleophiles have been studied. Reaction of 1 with alcohols, triethylsilane, allyltrimethylsilane, and methylthiotrimethylsilane in CH₂Cl₂ in the presence of TiCL₄, gave the substitution products 2,7a, 7b, and 7c in 80-90% yields. The substitution reaction took place chemoselectively on the hemiacetal group of I. Reaction of 1 with cyanotrimethylsilane in CH₂C1₂ in the presence of TiCL₄, gave compound 8 and the rearranged product 9. The structure of 9 was proven by X-ray analysis.     

Kinetics of styrene emulsion polymerization in the presence of montmorillonite

The effect of the pristine sodium montmorillonite (Na⁺-MMT) on the styrene emulsion polymerizations with different concentrations of SDS ([SDS]) was investigated. At constant [SDS], the polymerization rate is faster for the run with 1 wt.% Na⁺-MMT compared to the counterpart without Na⁺-MMT. Micelle nucleation predominates in the polymerizations with [SDS] ≧ 13 mM. On the other hand, the contribution of the polymerization associated with the Na⁺-MMT platelets increases significantly when [SDS] decreases from 13 to 9 mM. At [SDS] (e.g., 2 mM) < CMC, homogeneous nucleation controls the particle formation process and polymerization kinetics. Moreover, the contribution of the Na⁺-MMT platelets that act as extra reaction loci to the polymerization kinetics is even comparable to the run in the absence of Na⁺-MMT. The resultant polymer particle size, polymer molecular weight and zeta potential were characterized and a preliminary model was developed to qualitatively study the differences between the polymerizations in the presence and absence of 1 wt.% Na⁺-MMT.     

Studies on quinazolines. 11. Intramolecular imidate-amide rearrangement of 2-substituted 4-(omega-chloroalkoxy)quinazoline derivatives. 1,3 -O --> N shift of chloroalkyl groups via cyclic 1,3-azaoxonium intermediates

The omega-chloroalkylation of 2-substituted quinazolin-4(3H)-one derivatives 1 and 2 with Br-(CH(2))(n)-Cl (n = 2-4) and the intramolecular imidate-amide rearrangement of the alkylated products are described. At room temperature, the 2-phenyl substituent promoted O-alkylation, whereas the less steric 2-benzyl group led to a higher ratio of N-alkylation. The investigation of the O-alkylated products, 4-omega-chloroalkoxyquinazolines, revealed that the migration of omega-chloroethyl and omega-chloropropyl groups from oxygen to nitrogen should be intramolecular via five- and six-membered cyclic 1,3-azaoxonium intermediates, respectively. Competition between rearrangement and nucleophilic substitution results in the formation of 7a,b and 8a,b from the nucleophilic substitution of 4a,b and 6a,b, respectively.     

Condensed 1,3-benzothiazinones. 1. Facile synthesis of 2-amino-1,2,4-triazolo[5,1-b][1,3]-benzothiazin-9-one

Treating 2-mercaptobenzohydrazide ( 1a ) with cyanogen bromide gave 3-amino-2-imino-3,4-dihydro-2.H-1,3-benzothiazin-4-one ( 2a ). This compound underwent further cyclocondensation with a second molecule of cyanogen bromide or S-methylisothiourea sulfate to afford the biologically interesting 2-amino-1,2,4-triazolo-[5,1-b][1,3]benzothiazin-9-one ( 3c ). Compound 3c could also be prepared directly from 1a by treating with excess amount of cyanogen bromide in more satisfactory yield.     

The defect structure of CdTe: Self-diffusion data

Cadmium and Te tracer self-diffusion was studied for pure and indium-doped CdTe. Analysis of the results leads to a point defect model in which imperfections with various charges play a role. Expressions for the tracer diffusion coefficients by various mechanisms and for the diffusion coefficients of individual point defects are derived.     

Simulation of non‐linear free surface motions in a cylindrical domain using a Chebyshev–Fourier spectral collocation method

When a liquid is perturbed, its free surface may experience highly non‐linear motions in response. This paper presents a numerical model of the three‐dimensional hydrodynamics of an inviscid liquid with a free surface. The mathematical model is based on potential theory in cylindrical co‐ordinates with a σ‐transformation applied between the bed and free surface in the vertical direction. Chebyshev spectral elements discretize space in the vertical and radial directions; Fourier spectral elements are used in the angular direction. Higher derivatives are approximated using a collocation (or pseudo‐spectral) matrix method. The numerical scheme is validated for non‐linear transient sloshing waves in a cylindrical tank containing a circular surface‐piercing cylinder at its centre. Excellent agreement is obtained with Ma and Wu's [Second order transient waves around a vertical cylinder in a tank. Journal of Hydrodynamics 1995; Ser. B4 : 72–81] second‐order potential theory. Further evidence for the capability of the scheme to predict complicated three‐dimensional, and highly non‐linear, free surface motions is given by the evolution of an impulse wave in a cylindrical tank and in an open domain. Copyright © 2001 John Wiley & Sons, Ltd.     

Congruences for partition functions related to mock theta functions

The Ramanujan Journal - Partitions associated with mock theta functions have received a great deal of attention in the literature. Recently, Choi and Kim derived several partition identities from...