Design, Synthesis and Suzuki-Miyaura Cross-Coupling Reactions of Potassium Organotrifluoroborates

The Suzuki–Miyaura cross-coupling reaction is one of the most efficient methods to form new carbon-carbon bonds, allowing a rapid increase in complexity among target molecules of interest. Among a variety of boron reagents utilized in Suzuki–Miyaura reactions, potassium organotrifluoroborates are of great interest because they have many advantages over other boron reagents. Organotrifluoroborates, which are tetracoordinate boron species, show better stability and reactivity, and they are much less prone to protodeboronation. α-Chiral β-arylated carbonyl compounds are important substructures in organic chemistry, and their preparations, such as benzylations, asymmetric hydrogenations, and conjugate additions, have been studied. However, these methods have limitations in terms of selectivity and functional group tolerance. We developed a more direct method that could overcome the problems. Enantiomerically enriched potassium α-chiral β-trifluoroboratoamides were prepared, and the general conditions were found to couple successfully with various aryl and hetaryl chlorides to afford the corresponding α-chiral β-arylated carbonyl compounds. Moreover, the diastereoselectivities were greater than 95:5, and retained throughout the coupling reactions. Aminomethyl moieties are readily encountered in biologically active compounds as well as in organic intermediates. Even though several synthetic methods have been reported, the means of preparation of these subunits are still limited. We developed a more efficient method to access aminomethyl substructures by preparation of air stable potassium Boc-protected primary and secondary aminomethyltrifluoroborates. The Suzuki–Miyaura cross-coupling reaction was investigated with these new aminomethylating boron reagents to provide the corresponding aminomethyl moieties. Aryl and hetaryl chlorides, mesylates, and sulfamates were proved to be effective electrophilic coupling partners under developed conditions. These methods provide a complementary way to access important building blocks that is more direct and general than currently available methods

Formal Synthesis of Premisakinolide A and C(19)–C(32) of Swinholide A via Site-Selective C–H Allylation and Crotylation of Unprotected Diols

Using stereo- and site-selective C–H allylation and crotylation of unprotected diols, an intermediate in the synthesis of premisakinolide A (bistheonellic acid B) that was previously made in 16–27 (LLS) steps is now prepared in only nine steps. This fragment also represents a synthesis of C(19)–C(32) of the actin-binding macrodiolide swinholide A

Pd-Catalyzed Suzuki–Miyaura Cross-Coupling Reactions between Sulfamates and Potassium Boc-Protected Aminomethyltrifluoroborates

Sulfamates were studied as the electrophilic partners in the palladium-catalyzed Suzuki–Miyaura cross-coupling reaction with potassium Boc-protected primary and secondary aminomethyltrifluoroborates. A broad range of substrates was successfully coupled to provide the desired products. Complex molecules containing a new carbon–carbon bond and an aminomethyl moiety could be prepared through this developed method

Suzuki–Miyaura Cross-Coupling Reactions of Potassium Boc-Protected Aminomethyltrifluoroborate with Aryl and Hetaryl Mesylates

Palladium-catalyzed Suzuki–Miyaura cross-coupling reactions were studied with potassium Boc-protected aminomethyltrifluoroborate through C–O activation of various mesylate derivatives to afford the corresponding products in moderate to good yields

Recent Advances in One-Pot Modular Synthesis of 2-Quinolones

It is known that 2-quinolones are broadly applicable chemical structures in medicinal and agrochemical research as well as various functional materials. A number of current publications about their synthesis and their applications emphasize the importance of these small molecules. The early synthetic chemistry originated from the same principle of the classical Friedländer and Knorr procedures for the preparation of quinolines. The analogous processes were developed by applying new synthetic tools such as novel catalysts, the microwave irradiation method, etc., whereas recent innovations in new bond forming reactions have allowed for novel strategies to construct the core structures of 2-quinolones beyond the bond disconnections based on two classical reactions. Over the last few decades, some reviews on structure-based, catalyst-based, and bioactivity-based studies have been released. In this focused review, we extensively surveyed recent examples of one-pot reactions, particularly in view of modular approaches. Thus, the contents are categorized as three major sections (two-, three-, and four-component reactions) according to the number of reagents that ultimately compose atoms of the core structures of 2-quinolones. The collected synthetic methods are discussed from the perspectives of strategy, efficiency, selectivity, and reaction mechanism

Total Synthesis of Swinholide A: An Exposition in Hydrogen-Mediated C–C Bond Formation

Diverse hydrogen-mediated C–C couplings enable construction of the actin-binding marine polyketide swinholide A in only 15 steps (longest linear sequence), roughly half the steps required in two prior total syntheses. The redox-economy, chemo- and stereo­selectivity embodied by this new class of C–C couplings are shown to evoke a step-change in efficiency