II. Structure Elucidation on Polyketide Antibiotics by Biosynthetic Means A. Elasnin B. Herbimycin C. Irumamycin D. Phthoramycin E. Aurantinin F. Xanthoquinodin III. Biosynthesis and Stereochemistry of Macrolide Antibiotics and Production of New Hybrid Macrolides and Polyketide A. Biosynthesis of the Aglycone Moiety in 16-Membered Macrolides, Leucomycins and Tylosin B. The Intact Incorporation ...

A new approach for the synthesis of 4-oxo-3-quinolinecarboxylic acid derivatives is described. This methodology involves the C-acylation of the anions of appropriate beta-keto esters with novel N-hydroxysuccinimide esters of anthranilic acids. The intermediate C-acylation products 3 are spontaneously cyclized to afford 3-ethoxycarbonyl-4-oxoquinoline derivatives 4. The introduction of a variety...

In August 2009 the Sun illuminated Saturn's rings from almost exactly edge-on, revealing a subtle corrugation that extends across the entire C ring. This corrugation's amplitude is 2 to 20 meters and its wavelength is 30 to 80 kilometers. Radial trends in the corrugation's wavelength indicate that this structure--like a similar corrugation previously identified in the D ring--results from diffe...

The reaction of tetraarylbutatrienes (tetraaryl[3]cumulenes) with tetracyanoethene (TCNE), a strong electron-accepting molecule, at room temperature yielded novel four-membered ring compounds (head-to-tail unsymmetrically substituted diarylallene dimers) by [2 + 2] cycloaddition of the central C=C bond of the butatrienes. This reaction proceeded through a head-to-head symmetrically substituted ...

UV photolysis of (iodomethyl)cyclopropane yielded 3-buten-1-yl instead cyclopropylcarbinyl, the expected product photolytic C-I bond cleavage. This result suggests that ring opening intermediate cyclopropylcarbinyl even at T ~10 K proceeds too fast to be measured via this technique. finding is in agreement with earlier theoretical studies which predicted rapid decay heavy-atom tunneling. In an ...

This paper studies the homomorphism of rings of continuous functions ρ:C(X) → C(Y ), Y a subspace of a Tychonoff space X, induced by restriction. We ask when ρ is an epimorphism in the categorical sense. There are several appropriate categories: we look at CR, all commutative rings, and R/N, all reduced commutative rings. When X is first countable and perfectly normal (e.g., a metric space), ρ ...

In this paper, we establish the generalized Hyers–Ulam–Rassias stability of C-ternary ring homomorphisms associated to the Trif functional equation d · C d−2f( x1 + · · ·+ xd d ) + C d−2 d ∑

An extremely rare case of a "primary endometrial adenocarcinoma with signet-ring cells" is presented in this study with microscopical images of the characteristic coexistence of the tumour and intermediate precancerous areas containing signet-ring cells.

[κ2-O,O′-Carbonatotetraamminecobalt(III)] iodide, or [Co(NH3)4CO3]I, named in this paper as compound 1, was prepared and characterized comprehensively with spectroscopic (IR, Raman UV) single-crystal X-ray diffraction methods. Compound 1 orthorhombic, isomorphous the analogous bromide. The four ammonia ligands carbonate anion were coordinated to central cobalt cation a distorted octahedral geom...