English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The benzothiazole moiety has been found in a variety of natural products and pharmaceuticals and demonstrates efficient biological activities. Specifically, 2-substituted benzothiazole derivatives have attracted considerable attention in a wide spectrum of chemical applications due to their unique structural properties. Therefore, the diversity of synthetic protocols has been an extensively discussed topic among scientists involved in organic synthesis for the past decades. In general, to build up the 2-substituted benzothiazole complexes, the strategic tools can be categorized as shown in Scheme 1: cross-coupling of benzothiazolylmetallic complexes (method A), coupling reaction of benzothiazole via direct oxidative C-H activation (method B), crosscoupling of organometallic with halobenzothiazole (method C), and ring-construction of N and S-containing compounds with the appropriate substrates (method D). Among these tools, methods B and D have been extensively explored. In contrast, in spite of the effectiveness and efficiency of the transition metal-containing organometallic complexes, methods A and C are relatively undeveloped. Interestingly, there is no report of synthesis utilizing method A, likely owing to the difficulty of preparing the corresponding organometallic reagents. In our continuing study on the application of organozinc reagents, we found that stable 2benzothiazolylzinc bromide (I) was easily prepared by the direct insertion of highly active zinc into 2-bromobenzothiazole. The subsequent coupling reactions of the resulting organozinc reagent with several different types of electrophiles yielded the desired products in a moderate yield. To the best of our knowledge, this is the first general example of the direct preparation of 2-benzothiazolylzinc bromide and the subsequent transition metal-catalyzed cross-coupling reactions to generate 2-substituted benzothiazole derivatives. The new organozinc reagent (I) was efficiently prepared by the reaction of active zinc with 2-bromobenzothiazole at room temperature in THF. The oxidative addition of active zinc (1.5 equiv used) was completed in 3 h at room temperature. This organozinc reagent has been found to be very effective for cross-coupling reactions with a variety of aryl iodides in the presence of a catalytic amount of Pd(PPh3)2Cl2 in THF at room temperature giving rise to corresponding 2arylbenzothiazoles. The results are summarized in Table 1. This catalytic system was also effective for the coupling reaction with haloaromatic compounds containing relatively acidic protons. As shown in Table 2, the cross-coupling products (2a-2d, Table 2) were obtained in moderate yields from the Pd(II)-catalyzed coupling reaction with the corresponding iodinated anilines and phenols. Compared to the outstanding progress of the synthetic protocol for 2-arylbenzothiazole as summarized in Scheme Scheme 1. General approaches for the generation of 2-substituted benzothiazoles.

bulletin of the korean chemical society

Direct Preparation of 2-Benzothiazolylzinc Bromide and its Applications: A Facile Synthetic Route to the Preparation of 2-Substituted Benzothiazole Derivatives