9H-Pyrrolo[1,2-a]indoles

Mazzola, Vincent J.; Bernady, Karel F.; Franck, Richard W.

doi:10.1021/jo01288a060

Cited by 33 publications

(19 citation statements)

References 6 publications

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“…These results are of interest in view of the fact that mitomycins 10 bear a Me group at Structural Analyses. ~ The unsubstituted products 6a-9a are known compounds; their physical properties agree with those reported in the literature: [19-211 for 6a, [22] for 7a, [9], and [23] for 8a, [8] for 9a. Interestingly, the NMR data of 9a proved to be strictly identical with those reported in [23].…”

Section: ' )supporting

confidence: 81%

Cascade Reactions. A Simple One‐pot Synthesis of the Mitomycin Skeleton

Defoin

Geffroy

Nouën

et al. 1989

Helvetica Chimica Acta

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~ ~Nitroso-arene dienophiles 1 react regiospecifically with the conjugated dienals 2 and 3a/3b, and lead thereby to the unstable Dzels-Alder cycloadducts 4 and 5 These undergo two types of cascade reactions which give pyridmium betaines 6 and pyrrolo-indoles 8 as the major reaction products The one-pot syntheses of pyrroloindoles 8 represent a new and easy access to the basic skeleton of mitomycins 10 The scope and limitations of the cascade reactions were investigated Diels-Alder Cycloadditions of Nitroso-arene Dienophiles with Conjugated Dienals and their Cascade Reactions'). -We shall describe herein some cascade-reaction sequences which we observed, when conjugated dienals were treated with nitrosoarene dienophiles 1. To our knowledge, no cycloaddition reactions have been described so far between nitroso dienophiles and linear conjugated dienals. Nevertheless, some oximeand dimethylacetal derivatives of these dienals are known to undergo Diels-Alder reactions with nitroso dienophiles [2-71.The reaction of nitrosobenzene with pentadienal2 or with the commercially available mixture of hexadienals 3a (80 YO) and 3b (20 YO) occurred rapidly leading, in each instance, to four heterocyclic products, none of which being the expected primary Diels-Alder adduct. For example, the reaction of pentadienal 2 with PhNO gave the betaine 6a, trace amounts of the pyrrole-2-carbaldehyde 7a, the tricyclic alcohol 8a, and the corresponding ketone 9a (Scheme I). It should be noted that the preparation of the tricyclic products 8a and 9a, via a different multistep approach, had already been described as part of a synthetic plan for the mitomycins [8-lo].Mitomycins 10 represent a class of well-known natural products [l 11 which exhibit antibiotic and antitumor properties [12].Since our procedure for the synthesis of pyrrolo-indoles 8a/8b and 9a/9b represents a new one-pot process, using easily available starting materials, we decided to investigate the scope and limitations as well as the mechanism of these obviously complex cascade reactions (see below), our ultimate goal being the synthesis of some mitomycin derivatives.

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Section: ' )supporting

confidence: 81%

Cascade Reactions. A Simple One‐pot Synthesis of the Mitomycin Skeleton

Defoin

Geffroy

Nouën

et al. 1989

Helvetica Chimica Acta

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“…Flash column chromatography was performed by using a CombiFlash (Teledyne ISCO). 1 [12] Compound 4b was prepared from 3b (2.65 g, 7.24 mmol) by using the method described for compound 4a. The chemical shifts (δ) are reported in parts per million (ppm) and the coupling constants (J) in Hz.…”

Section: Discussionmentioning

confidence: 99%

Synthesis and Investigation of Solar‐Cell Photosensitizers Having a Fluorazone Backbone

et al. 2017

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A synthetic sequence for the preparation of fully conjugated 2,7-disubstituted fluorazone (9H-pyrrolo[1,2--a]indol-9-one) derivatives has been developed comprising an Elming–Clauson–Kaas-type pyrrole formation, POCl3-mediated ring closure, selective halogenation and elongation of the conjugated backbone through cross-coupling reactions. As a proof of principle, this methodology was used to prepare for the first time two organic D–π–A dyes containing the fluorazone moiety. The new compounds display broad absorption bands in the visible-light region when adsorbed on nanocrystalline TiO2 and electrochemical properties compatible with their employment as photosensitizers in dye-sensitized solar cells. Small-scale photovoltaic devices fabricated with the fluorazone dyes yielded power conversion efficiencies in the range of 2.1–2.4 %, which correspond to approximately 70 % of the efficiency obtained with the reference organic dye DF15 under the same conditions

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“…Previously attempted functionalization of 9H-pyrrolo[1,2-a]indole ( 338 ) [297] had remained relatively fruitless. [298] However, singlet oxygen oxidation in the presence of pyridine routinely gave 70% of 338 .…”

Section: The Mitomycins: Synthetic Studiesmentioning

confidence: 99%