Switchable and Scalable Heteroarylation of Primary Amines with 2-Chlorobenzothiazoles under Transition-Metal-Free and Solvent-Free Conditions

Abstract

2-Aminobenzothiazoles comprise a valuable structural motif, which prevails in versatile natural products and biologically active compounds. Herein, a switchable and scalable C–N coupling protocol was developed for the synthesis of these compounds from 2-chlorobenzothiazoles and primary amines. Gratifyingly, this protocol was achieved under transition-metal-free and solvent-free conditions. Moreover, introducing an appropriate amount of NaH completely switched the selectivity from mono- toward di-heteroarylation, and further investigations provided a rationale for this new finding. Furthermore, gram-scale synthesis of representative products 3a and 4a was realized by applying operationally simple and glovebox-free procedures, which revealed the practical usefulness of this work. Finally, evaluation of the quantitative green metrics provided evidence that our protocol was superior over the literature ones in terms of green chemistry and sustainability.

Cs2CO3‐Promoted C−O Coupling Protocol Enables Solventless (Hetero)aryl Ether Synthesis under Air Atmosphere

“…Despite the successful development of several C−N coupling protocols in our previous efforts, [9b,12b, c, 20] the initial hit in this work implicated the excellent selectivity of C−O vs . C−N coupling if a mixture of 1 a , LiO t Bu, aniline and ethanol was heated at 120 °C for 16 h (as detailed in Scheme S1).…”

Cellulose@PO3H: As an Efficient and Recyclable Ionic Liquid-Enabled Catalytic Greener Approach to One-Step Synthesis of Flavoring Ketones

“…Finally, based on green metrics, this study includes atom economy (AE), environmental-factor (E-factor), mass intensity (MI), mass productivity (MP), effective mass yield (EMY), and solvent intensity (SI), as shown in Table . Subsequently, the abovementioned green metrics protocols based on the highlighted literature protocol are calculated in Supporting Information Table S2 (Supporting Information, Scheme 1a–e). − …”

One‐Pot Synthesis of N‐Benzyl/Allyl‐N‐phenyl‐2‐benzothiazolamines from 1‐(2‐Iodophenyl)‐3‐phenylthioureas and Benzyl/Allyl Halides

“…presented a convenient method for the preparation of 2‐substituted benzothiazoles from N ‐substituted‐ N ‐(2‐halophenyl)thioureas via a base‐promoted cyclization (Scheme 1, c). Chen et al [23] . developed a scalable protocol of the C−N cross‐coupling between 2‐chlorobenzothiazoles and primary amines (Scheme 1, d).…”