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A Zinc-Mediated Deprotective Annulation Approach to New Polycyclic Heterocycles.

ABSTRACT: A straightforward approach to new polycyclic heterocycles, 1H-benzo[4,5]imidazo[1,2-c][1,3]oxazin-1-ones, is presented. It is based on the ZnCl2-promoted deprotective 6-endo-dig heterocyclization of N-Boc-2-alkynylbenzimidazoles under mild conditions (CH2Cl2, 40 °C for 3 h). The zinc center plays a dual role, as it promotes Boc deprotection (with formation of the tert-butyl carbocation, which can be trapped by substrates bearing a nucleophilic group) and activates the triple bond toward intramolecular nucleophilic attack by the carbamate group. The structure of representative products has been confirmed by X-ray diffraction analysis.

SUBMITTER: Veltri L

PROVIDER: S-EPMC8072660 | biostudies-literature | 2021 Apr

REPOSITORIES: biostudies-literature

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A Zinc-Mediated Deprotective Annulation Approach to New Polycyclic Heterocycles.

Veltri Lucia L Amuso Roberta R Petrilli Marzia M Cuocci Corrado C Chiacchio Maria A MA Vitale Paola P Gabriele Bartolo B

Molecules (Basel, Switzerland) 20210416 8

A straightforward approach to new polycyclic heterocycles, 1H-benzo[4,5]imidazo[1,2-c][1,3]oxazin-1-ones, is presented. It is based on the ZnCl2-promoted deprotective 6-endo-dig heterocyclization of N-Boc-2-alkynylbenzimidazoles under mild conditions (CH2Cl2, 40 °C for 3 h). The zinc center plays a dual role, as it promotes Boc deprotection (with formation of the tert-butyl carbocation, which can be trapped by substrates ...[more]

PMID: 33923572

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