The first example of an intramolecular Westphal reaction. Synthesis of a new aza-quinolizinium type system

Martínez-Barrasa, Valentín; Burgos, Carolina; Izquierdo, M. Luisa; Alvárez‐Builla, Julio; Vaquero, Juan J.

doi:10.1016/s0040-4039(99)00696-6

Cited by 9 publications

(2 citation statements)

References 22 publications

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“…[17][18][19][20][21][22] The search in our lab for new azaquinolizinium-type cations having the requisites previously established for intercalation led us to focus on different possibilities for incorporating the azaquinolizinium moiety into a nonlinearly fused tetracyclic cation. The retrosynthetic analysis of one of the desired systems (Scheme 2) indicated that the intramolecular Westphal reaction 23 could be the choice for a straightforward synthesis of benzo [f]pyrido[2,1-a]phthalazinium cations 3 from the salt 10, which was envisioned to originate from the alkene 8. Thus, our approach was to use isocromane 5 as the key raw material, convert it to a 2-haloethyl benzaldehyde 6, and prepare 8 through a Wittig reaction.…”

Section: Chemistrymentioning

confidence: 99%

Benzo[f]azino[2,1-a]phthalazinium Cations: Novel DNA Intercalating Chromophores with Antiproliferative Activity

et al. 2004

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New azaquinolizinium-type cations have been obtained from isochromane. The synthesis was completed over seven steps and included as the key feature an intramolecular Westphal condensation. This first example of the intramolecular process allowed the preparation of benzo[f]pyrido[2,1-a]phthalazinium and benzo[f]quino[2,1-a]phthalazinium salts, which were evaluated as DNA intercalators, DNA topoisomerase I inhibitors, and antiproliferative compounds. Both cationic systems behave as DNA intercalators and exhibit antiproliferative activity. The pentacyclic benzo[f]quino[2,1-a]phthalazinium cations also have an inhibitory effect on the catalytic activity of DNA topoisomerase I, without trapping of cleavage complexes. Structural characterization using density functional theory indicates that the fused ring systems are slightly nonplanar, and additional molecular modeling studies suggest a preferred orientation for the intercalating chromophores within a typical CpG or TpG intercalation site.

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Section: Chemistrymentioning

confidence: 99%

Benzo[f]azino[2,1-a]phthalazinium Cations: Novel DNA Intercalating Chromophores with Antiproliferative Activity

et al. 2004

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“…375 When treated with Br 2 under light-irradiation, isochromenones are regioselectively halogenated adjacent to oxygen (Scheme 251). 376 The resulting species are prone to ringopening, which can be performed by adsorption on silica gel and subjection to microwave irradiation, affording 2-(2-bromoethyl)benzaldehyde 950a in good yield. Analogously, brominated benzophenones 950b-e were synthesized in reasonable to excellent yields from 1-phenylisochromanes 949b-e. 234…”

Section: Radical Halogenationsmentioning

confidence: 99%