Novel tricyclic heterocycles (benzopyrrocolines) arising via carbanion attack on a nitrile function

A new reaction of 2-n-alkanoyl-1,2-dihydroisoquinaldonitriles 1 (isoquinoline Reissert compounds) has been discovered. As previously reported reaction of the conjugate bases of Reissert compounds with alkyl halides yields the corresponding 1-alkyl derivatives 2 . However, compounds 2 , R = n-alkyl, with only a catalytic amount of bases form the enolate ion, which attacks the neighboring nitrile functionality to produce directly in the same reaction vessel excellent yields of benzopyrrocoline derivatives 5-10 . The nmr spectrum reveals a solvent dependent tautomeric equilibrium between ketoeneamine ( a ) and ketoimine ( b ) forms. Unlike compounds 2 the double bonds of the pyridine ring of compounds 7 and 8 were readily reduced with hydrogen. Thus, n-alkanoyl Reissert compounds afford a convenient route to the corresponding benzopyrroco-lines.     

On three Krein extension problems and some generalizations

Three basic extension problems which were initiated by M. G. Krein are discussed and further developed. Connections with interpolation problems in the Carathéodory class are explained. Some tangential and bitangential versions are considered. Full characterizations of the classes of resolvent matrices for these problems are given and formulas for the resolvent matrices of left tangential problems are obtained using reproducing kernel Hilbert space methods.Dedicated to the memory of M. G. Krein, a beacon for us both.The authors wish to acknowledge the partial support of the Israel-Ukraine Exchange Program. D. Z. Arov also wishes to thank the Weizmann Institute of Science for partial support and hospitality; H. Dym wishes to thank Renee and Jay Weiss for endowing the chair which supports his research.     

Reduced variable molecular dynamics

This article describes an extension to previously developed constraint techniques. These enhanced constraint methods will enable the study of large computational chemistry problems that cannot be easily handled with current constrained molecular dynamics (MD) methods. These methods are based on an O(N) solution to the constrained equations of motion. The benefits of this approach are that (1) the system constraints are solved exactly at each time step, (2) the solution algorithm is noniterative, (3) the algorithm is recursive and scales as O(N), (4) the algorithm is numerically stable, (5) the algorithm is highly amenable to parallel processing, and (6) potentially greater integration step sizes are possible. It is anticipated that application of this methodology will provide a 10- to 100-improvement in the speed of a large molecular trajectory as compared with the time required to run a conventional atomistic unconstrained simulation. It is, therefore, anticipated that this methodology will provide an enabling capacity for pursuing the drug discovery process for large molecular systems. © 1995 John Wiley & Sons, Inc.     

The theoretical basis and phenomenology of the OZI rule

No reliable theoretical recipe exists for predicting strengths of OZI-forbidden transitions proceeding via two OZI-allowed transitions like φ→K⁺K^?→?π, π^?p→K⁺K^?n→φφn or π^?p→ηn→φφn. Nonet symmetry, exchange degeneracy and duality suppress such transitions by cancellations between different diagrams. Unpredictable OZI violations are introduced by breaking of these symmetries. Phenomenological analyses of charmonium decays and meson photoproduction establish an emperical topological criterion for classifying some processes as less forbidden and suggest that π^?p→φφn should not be suppressed by a factor of more than three in amplitude. Its observation is not conclusive evidence for new exotic particles.     

Low-and high-dimension limits of a phase separation model

We study a simple zero-temperature model for phase separation of a binary alloy, in which nearest-neighbor interchange can occur if the fraction of AB pairs is not thereby increased. We present analytic results for the one-dimensional case and numerical results for the infinite dimensionality limit on a Cayley tree. In neither limit does the final fraction of AB pairs agree with the dimension-independent result found previously ind=3, 4, 5.     

The ordinality of additively generated sets

Presented by Jan Mycielski.     

Studies in the formation of poly(oxazolidone)s. III. Catalysis and kinetics of the model oxazolidone formation from cyclohexyl isocyanate and phenylglycidyl ether

The reaction of cyclohexyl isocyanate with phenylglycidyl ether was selected as model reaction for the synthesis of cycloaliphatic isocyanate-based poly(2-oxazolidone)s. The selectivity of AlCl₃ and AlCl₃-triphenylphosphine oxide (AlCl₃–TPPO) and AlCl₃-hexamethylphosphoric triamide (AlCl₃–HMPA) complexes was studied for 2-oxazolidone formation. The reaction products were identified by means of the melting point, ¹H-NMR, and IR spectroscopy. The kinetics of the model reaction was studied using AlCl₃-TPPO in o-dichlorobenzene at 120 and 140°C.