Indoles spectroscopy

UV spectroscopy, 4, 178, 179 vertical resonance energy, 4, 191 Vilsmeier-Haack formylation, 4, 221, 222 3H-Indoles... 

Two important books on the biogenesis of indole alkaloids have been published (5, 6), therefore we do not intend to cover the literature of the biogenesis of corynantheine- and yohimbine-type alkaloids. Our chapter begins with the structure elucidation of the alkaloids isolated during the past two decades and proceeds with the synthesis, transformation, as well as spectroscopy of the alkaloids in question. 

Results and data gathered on mass spectroscopy of various indole alkaloids have been summarized by Hesse (320). The derivation of the characteristic fragments of indolo[2,3-a]quinolizidines has been interpreted by Gribble and Nelson (321), who investigated C-3, C-5, C-6, C-20, and C-21 deuterated derivatives of octahydroindolo[2,3-a]quinolizine (1). Kametani et al. have observed and proved, with labeled compounds, a methyl transfer from the ester function of reserpine derivatives to the basic nitrogen atom during mass-spectroscopic measurement (322). 

Indoles have been shown by ultraviolet and nmr spectroscopy to be protonated predominantly at the 3-position, giving the conjugate acids [172] (Hinman and Whipple, 1962). Hydrogen exchange at... 

In 1990, Nakamura et al. reported for the first time the complete biosynthetic origin of the whole carbon skeleton of carbazomycin B isolated from lower plants (378). Based on feeding experiments with and C-labeled compounds, followed by measurement of radioactivity and C-NMR spectroscopy, it was shown that L-tryptophan (408) contributes to C-3 and C-4 of the hexasubstituted aromatic ring, in addition to the indole ring, indicating tryptophan as the progenitor of carbazomycin B (261), in contrast to Chakraborty s proposal of 2-methylcarbazole. The indole part of L-tryptophan (408) is formed by incorporation of two carbons from phosphor-ibosyl diphosphate (430), with loss of the anthraniiic acid (397) carboxyl. The... 

The reaction between A-chlorobenzotriazole and l-methyl-2-phenylindole involves formation of the indole radical cation and benzotriazole radical via an initial electron transfer <82JOC4895, 91JCS(P2)1779>. Chemical reactions of benzotriazole on a freshly etched surface of metallic copper are studied by surface-enhanced Raman scattering, x-ray photoelectron spectroscopy, and cyclic voltammetry. The surface product is (benzotriazolato)copper(-l-), which covers the surface in the shape of polymeric material and shows good anticorrosion effects for copper <91JPC7380>. 

The epoxidation of heteroarenes such as furans and indoles generates very labile products, such that the reaction needs to be carried out at subambient temperature. For example, even at —20°C, the epoxide of 2,3-drmethylbenzofuran rearranges to the ortho-quinomethide (equation 5) . To characterize this epoxide by H-NMR spectroscopy, the fully deuteriated DMD-dg solution, prepared in acetone-dg, was employed for the oxidation and the epoxide was detected at —78 °C . Alkynes lead on epoxidation to a multitude of oxidation products (equation 6) thus, the reaction is synthetically hardly useful and, therefore, has been little studied . ... 

The preparation and study of tautomers derived from 2-(2 -pyridyl)indole, 2-(2 -pyrrolo)[l,8]naphthyridine, and related heterocycles has been undertaken using ultraviolet (UV) and nuclear magnetic resonance (NMR) spectroscopy and also by molecular orbital (MO) calculations <1998JOC4055>. 

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