The willgerodt-kindler reactions. 7. The mechanisms

The mechanisms involved in various stages of the Kindler Reaction are discussed, with particular attention especially to its most unusual feature: the movement of a carbonyl group from methylene carbon to methylene carbon in an unbranched alkyl chain, or around a cycloalkyl ring. The first step is the reversible formation of an enamine, which is attacked by a catalyst generated from sulfur and the amine solvent to form a highly reactive intermediate with a sulfur-containing heterocyclic ring. The natures of the catalytically active species and the reactive intermediates are proposed. Other steps involved in the Kindler Reaction are also discussed, as is the relationship of the Willgerodt Reaction to the Kindler Reaction.     

The freeon theory of magnetism. I. The Heisenberg interaction

The freeon theory of magnetism is a viable alternative to the well-known Heisenberg theory. In particular, the freeon-exchange theory provides a deeper insight into the nature of the magnetic interaction than does the spin-exchange theory. In addition, it avoids the superfluous M_S quantum number in zero-field splitting, the overcounting of spin states, the spin frustration, and the spin paradigm. The freeon-exchange theory employs the algebra of the symmetric group and/or the unitary group in place of the spin algebra. The basis vectors of freeon theory are the Gel'fand states which are uniquely labeled by Gel'fand diagrams; the latter provide both the electron configuration and the spin quantum number. Both the spin and the freeon formulations support the Landé interval rule. In this article, we apply freeon theory to transition-metal dimers, trimers, and tetramers; these are examples of molecular magnets which have applications to microcircuitry. The freeon theory follows the permutation-group principle laid down by Herman Weyl over one-half a century ago. © 1997 John Wiley & Sons, Inc. Int J Quant Chem 65 : 287–297, 1997     

The NCI Drug Information System. 3. The DIS Chemistry Module

The Chemistry Module of the Drug Information System (DIS) handles a database of 400,000 structures. New or modified records are created in this database on a daily basis and are merged into the file promptly. The Chemistry database is searchable in a wide variety of ways and provides novel methods for both input and output of chemical structures.     

The I.P. Alimarin Prize

Chronicle

The I.P. Alimarin Prize     

The tube electrode and e.s.r.

The convective diffusion equation for the downstream distribution of products and intermediates produced on a tube electrode under conditions of laminar flow is solved. For distances which are large compared to the thickness of the electrode, an analytical solution in real space can be found. The solution of the equation has been applied to an apparatus in which the intermediates and products are detected by e.s.r. The species are transported by laminar flow from the electrode through an e.s.r. cavity. Results are presented for two systems and are found to be in good agreement with the theory.     

The glycosides ofApocynum androsaemifolium L. II. The structure of apobioside

The roots of the plantApocynum androsaemifolium L. contain a new steroid diglycoside, apobioside, which has the structure cannogenin-(3)--D-cymaropyranoside-(4)--D-glucopyranoside.Khimiya prirodnykh soedinenii, Vol. 1, No. 1, pp. 15–22, 1965     

The nonribosomal code.

How genes are expressed and translated into proteins (using mRNA, codons and tRNAs as adaptor molecules) forms the basis of the 'genetic code'. Many peptides are synthesized nonribosomally, however, by large protein complexes that also serve as templates. Recent advances have shed light on what the nonribosomal code is and how it can be read.