Nature of zircon clastics in the Riphean and Vendian sandstones of the Southern Urals

New age dates of detrital zircons of terrigenous rocks augmented the possibilities of interpretation of their provenance. Unfortunately this interpretation is restricted by a formal comparison of age-and-composition characteristics of detrital crystals with any very distant model objects. The paper deals with a situation when the role of a source of a detritus is claimed by local objects. When comparing the age parameters of primary and detrital crystals of zircons, the data on Riphean volcanics and ancient metamorphics of the Taratash complex of the Southern Urals were used. Specifying the ideas on the nature of the zircon clastics (detritus) and its relationships with primary zircons of sources, a role of processes of mechanical abrasion is pointed out, leading to a clearing of heterogenous primary grains of defect crystals, which results in an accumulation of crystals of more homogenous appearance. The analysis of SHRIMP and TIMS-dates of zircons and U and Th concentrations in them, and also a comparison of histograms of primary zircons from Riphean volcanics and rocks of the Taratash complex on one hand and the detrital zircons from the Vendian and Riphean sandstones of the Southern Urals on the other, have shown that the age variations of both are rather comparable. It means that the age characteristics of primary zircons from the Riphean volcanics and rocks of the Taratash complex as sources of zircon clastics for the Riphean and Vendian sandstones are regulated by processes of resedimentation, and a detrital fraction of zircons is formed at the expense of local objects. The participation of very distant sources is not excluded, but in our case it is not detected

Formation of tetrahydropyrrolo[1,2-c]pyrimidines from acetylenes and piperidin-4-one oximes

[No abstract available

Reaction of 9-hydroxy(chloro, bromo)-4-azafluorene to bis[9-chloro(bromo-4-aza-fluoren-9-yl]

4-Aza-fluoren-9-ol and 9-chloro(bromo)-4-azafluorenes are converted in high yields upon refluxing with thionyl chloride to form bis[9-chloro(bromo)-4-azafluoren-9-yl]. At about 20‡C, azafluorenol and thionyl chloride form 9-chloro-4-azafluorene. Mechanisms are proposed for these reactions. © 1990 Plenum Publishing Corporation

N-allylation and N-benzylation of 2-phenylindole and its condensation with carbonyl compounds

By allylation and benzylation of 2-phenyl- and 2-phenyl-3-formylindole, N-allyl- and benzyl-substituted indoles have been obtained. By condensation of 2-phenylindole with 2-formylfluorene, and also with 4-aza- or 3-methyl-2-azafluorenone, compounds containing fragments of the indole, fluorene, and azafluorenone systems have been synthesized. In the interaction of 2-phenylindole or indole with formaldehyde and 2,5-dimethylpiperidin-4-one, depending on the temperature, bis(2-phenylindol-3-yl)methane, (2′,5′-dimethyl-4′-oxopiperidino)-(1-indolyl)methane, and bis(indol-3-yl)methane are formed. © 1993 Plenum Publishing Corporation

Preparation of 9-phenylethynyl-4-azafluoren-9-ol and 9-phenacylidene-4-azafluorene and their conversion to spiro compounds

9-Phenylethynyl-4-azafluoren-9-ol, which was obtained from 4-azafluorenone and phenylethynylmagnesium iodide, was used in syntheses of isomeric 9-phenacylidene-4-azafluorenes and spiro compounds with indene, indan, and pyrazoline fragments. It is assumed that the conversion of 9-phenacylidene derivatives to spiro compounds takes place via intramolecular substitution. © 1984 Plenum Publishing Corporation