Nitroindoles, structure

Gribble et al. (110,111) found that mtinchnones react smoothly with 2- and 3-nitroindoles to afford pyrrolo[3,4-h]indoles 200 and 201 (Table 10.5). In the case of unsymmetrical mtinchnones the regiochemistry, which can be very clean, does not follow simple FMO theory and probably results from a combination of electronic, steric, and dipole interactions. The structures of regioisomers were established... 

The crystal structure of an unmodified hanmierhead RNA in the absence of divalent metal ions has been solved. The X-ray crystal structure of the oligonucleotide d(GGCGAATTGG) has been described. It was designed to contain the d(G.GC)2 fragment and thus provide the basic repeat unit of a DNA triple helix. Parameters derived from this crystal structure enabled construction of models of both parallel and antiparallel triple helices. A variety of physical techniques has been used to investigate the structure of DNA containing the deoxyribosyl derivative 5-nitroindole. ... 

C-Ring substituted indoles, including 4-nitroindole, are also allylated under these conditions. The reaction is believed to proceed by an Sa I mechanism, with the Zn(03SCF3)2 acting as a Lewis acid catalyst. There may also be some N-H deprotonation by the amine. 1-Methylindole reacts under these conditions, but with reduced yield. The Zn(03SCF3)2-mediated reaction was used in tandem with intramolecular nucleophilic capture to synthesize the flustramine structure [89]. 

Chataigner and Piettre examined using a 3-nitroindole species in a domino process that would make use of an inverse electron demand Diels-Alder reaction, followed by a [3+2] cycloaddition with an electron-deficient olefin [110] (Scheme 67). They chose an aUtyl vinyl ether (318) as the electron-rich dienophile for the Diels-Alder step, and an acrylic acid ester (320) as the electron-poor olefin for the [3+2] reaction, hoping that the product from the multicomponent reaction (321) could then be reduced to form the tetracyclic structure 322. 

Fig. 11 The binding epitope of anti-lS5 was mapped through STD-NMR experiments [101]. The percentages drawn in the structure indicate the level of transfer of magnetization to a particular hydrogen relative to transfer received by the Af-acetyl methyl group. Large percentages were identified on the benzamide and the nitroindole, thus rationalizing the enhanced affinity of anti-lSS...

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