Pyrrole carboxamide introduction in the total synthesis of pyrrole–imidazole alkaloids

The pyrrole carboxamide is a characteristic structural feature found in the pyrrole–imidazole (oroidin) alkaloids, the various traditional and non-tradition methods for its introduction are reviewed herein.

QUANTITATIVE AND STRUCTURAL CHARACTERISTICS OF THE OIKONYMICON OF THE NORTHERN KHMELNYTSKYI REGION

In the Northern Khmelnytskyi region, we recorded 1,258 names of settlements, including 872 main oikonyms and 386 their variants. Among the nominations of the settlements we single out both the actual oikonyms – names of cities, towns, villages and microoikonyms – names of settlements, manors, farms and other similar small denotations. In the oikonym system, we distinguish between modern nominations and former ones, the number of which, as we can see, is almost the same, due to which the coefficient of dynamics of oikonymicon is 2,003, which means that on average settlement has two proper names. This is one of the highest rate due to the long (sometimes up to a thousand years) period of denotation and the presence of many extralingual factors that influenced the nomination of settlements. Traditionally, in modern onomastics, researchers divide onyms, according to their structure, into simple (monobasic), complex (two- and multi-basic) and compound (phrases and sentences) constructions. The largest number of analyzed oikonyms are simple names, represented by nouns. Thus, the proper names of settlements and their parts are quantitatively the largest groups of names of geographical objects of the Northern Khmelnytsky region. Quantitative differences can be traced territorially, as in Izyaslav district we recorded 1,459 (34.22%) such nominations, Polonskyi – 631 (14.8%), Slavutskyi – 998 (23.4%), and Shepetivskyi – 1176 (27, 58%); a total of 4,264 onyms. The coefficient of dynamics of such names is the highest among the proper names of cities, towns and villages, and the lowest – among the nominations of corners and neighborhoods. A characteristic structural feature of proper names of settlements and their parts is the dominance of simple forms over compound and especially complex ones.

Bismuth⋅⋅⋅π arene interaction in [Bi{OC6H4(CH2C6H5)-2}3]2

We report on the synthesis of a new bismuth aryloxide molecule Bi[OC6H4(CH2C6H5)-2]3 (1), which was characterized by NMR and IR spectroscopy as well as single-crystal X-ray diffraction analysis. A characteristic structural feature is the dimeric unit with a central Bi2O2 core resulting from μ-binding phenolates. In addition, both bismuth atoms show a Bi⋅⋅⋅π arene interaction with a quite short Bi⋅⋅⋅πcentroid distance of 3.11 Å in the solid state.

Synthesis of Xenia diterpenoids and related metabolites isolated from marine organisms

This review describes strategies for the chemical synthesis of xenicane diterpenoids and structurally related metabolites. Selected members from the four different subclasses of the Xenia diterpenoid family, the xenicins, xeniolides, xeniaphyllanes and xeniaethers, are presented. The synthetic strategies are discussed with an emphasis on the individual key reactions for the construction of the uncommon nine-membered carbocycle which is the characteristic structural feature of these natural products. Additionally, the putative biosynthetic pathway of xenicanes is illustrated.

A resonating-valence-bond theory of metals and intermetallic compounds

The resonating-valence-bond theory of metals discussed in this paper differs from the older theory in making use of all nine stable outer orbitals of the transition metals, for occupancy by unshared electrons and for use in bond formation; the number of valency electrons is consequently considered to be much larger for these metals than has been hitherto accepted. The metallic orbital, an extra orbital necessary for unsynchronized resonance of valence bonds, is considered to be the characteristic structural feature of a metal. It has been found possible to develop a system of metallic radii that perm its a detailed discussion to be given of the observed interatomic distances of a metal in term s of its electronic structure. Some peculiar metallic structures can be understood by use of the postulate that the most simple fractional bond orders correspond to the most stable modes of resonance of bonds. The existence of Brillouin zones is compatible with the resonating-valence-bond theory, and the new metallic valencies for metals and alloys with filled-zone properties can be correlated with the electron numbers for important Brillouin polyhedra.