Scalable Negishi Coupling between Organozinc Compounds and (Hetero)Aryl Bromides under Aerobic Conditions when using Bulk Water or Deep Eutectic Solvents with no Additional Ligands

Pd-catalyzed Negishi cross-coupling reactions between organozinc compounds and (hetero)aryl bromides have been reported when using bulk water as the reaction medium in the presence of NaCl or the biodegradable choline chloride/urea eutectic mixture. Both C(sp³ )-C(sp² ) and C(sp² )-C(sp² ) couplings have been found to proceed smoothly, with high chemoselectivity, under mild conditions (room temperature or 60 °C) in air, and in competition with protonolysis. Additional benefits include very short reaction times (20 s), good to excellent yields (up to 98 %), wide substrate scope, and the tolerance of a variety of functional groups. The proposed novel protocol is scalable, and the practicability of the method is further highlighted by an easy recycling of both the catalyst and the eutectic mixture or water.

Exploring the Application of the Negishi Reaction of HaloBODIPYs: Generality, Regioselectivity, and Synthetic Utility in the Development of BODIPY Laser Dyes

The generality of the palladium-catalyzed C-C coupling Negishi reaction when applied to haloBODIPYs is demonstrated on the basis of selected starting BODIPYs, including polyhalogenated and/or asymmetrical systems, and organozinc reagents. This reaction is an interesting synthetic tool in BODIPY chemistry, mainly because it allows a valuable regioselective postfunctionalization of BODIPY chromophores with different functional groups. In this way, functional patterns that are difficult to obtain by other procedures (e.g., asymmetrically functionalized BODIPYs involving halogenated positions) can now be made. The regioselectivity is achieved by controlling the reaction conditions and is based on almost-general reactivity preferences, and the nature of the involved halogens and their positions. This ability is exemplified by the preparation of a series of new BODIPY dyes with unprecedented substitution patterns allowing noticeable lasing properties.