Recent Advances in Nonprecious Metal Catalysis

Abstract

Nonprecious metal catalysis is a highly active area of research for both industrial and academic laboratories. New methods that efficiently generate useful functionality in cost-effective, high yielding, and environmentally friendly ways naturally garner attention from process chemists in many different industries. This series of highlights summarizes literature on the general topic of nonprecious metal catalysis over four-month timeframes and will focus on major trends in the field that are of general interest in the pharmaceutical industry. The first installment highlights selected transformations using copper, nickel, and iron catalysts.

Sustainable Access to 5‐Amino‐Oxazoles and Thiazoles via Calcium‐Catalyzed Elimination‐Cyclization with Isocyanides

“…The requirement to find reaction conditions that use more environmentally benign reagents is now a cornerstone of modern synthetic organic chemistry, with the introduction of the Twelve Principles of Green Chemistry cementing its importance within the community [1] . This has led to seminal work describing the use of non‐precious transition metals and main group organometallics in synthesis, [2] as well as the increase in the use of photo‐ [3] and electrochemistry [4] to mediate important transformations. Furthermore, the use of organocatalysis [5] and more sustainable radical initiators [6] have been successfully employed to produce important intermediates and complex scaffolds alike.…”

Recent Advances in Nonprecious Metal Catalysis

“…In air at room temperature, Ni(COD)-(DQ) was stored for 3 months, and no detectable decomposition was observed by 1 H NMR spectroscopy. In solution at room temperature, Ni(COD)(DQ) was stable for up to a week in non-degassed, non-anhydrous methanol-d 4 before partial decomposition was observed by 1 Ni-catalyzed cross-electrophile reductive coupling between aryl and alkyl halides has emerged as a useful method for C(sp 2 )−C(sp 3 ) bond formation and has captured the interest of process chemists. 6−9 This approach to form C(sp 2 )−C(sp 3 ) bonds avoids the need for pregenerated organometallic reagents and provides an alternative to the traditional crosscoupling reactions (e.g., Negishi, Kumada, and Suzuki couplings).…”

“…In solution at room temperature, Ni(COD)(DQ) was stable for up to a week in non-degassed, non-anhydrous methanol-d 4 before partial decomposition was observed by 1 Ni-catalyzed cross-electrophile reductive coupling between aryl and alkyl halides has emerged as a useful method for C(sp 2 )−C(sp 3 ) bond formation and has captured the interest of process chemists. 6−9 This approach to form C(sp 2 )−C(sp 3 ) bonds avoids the need for pregenerated organometallic reagents and provides an alternative to the traditional crosscoupling reactions (e.g., Negishi, Kumada, and Suzuki couplings). Inspired by a report by Hansen and Weix in which Pfizer's compound library was mined for possible ligands, 8 researchers at BI mined their compound library and identified 5-cyanoimidazole as a highly effective ligand for coupling neopentyl bromides with aryl bromides.…”

“…Several recent advances utilizing Katritzky salts as coupling partners were highlighted in the first installment of this review series. 3 Rasappan and co-workers contributed to the growing list of reactions by coupling acyl chlorides with Katritzky salts to form ketones in the presence of NiBr 2 •bpy (5−10 mol %) and Mn (1.8 equiv) as the reductant in a acetonitrile/N,Ndimethylacetamide (DMA) mixture (95:5) at room temperature. 48 A broad substrate scope was observed, and the products were isolated in good yields.…”

Iron-catalyzed domino coupling reactions of π-systems

“…Over the past couple decades, the use of transition-metal-catalyzed cross-coupling reactions have become a staple within the organic chemist's arsenal of carbon-carbon and carbon-heteroatom bond-forming reactions. Catalysis, as a synthetic tool, is widely employed to accomplish transformations to produce many various pharmaceuticals, polymeric materials, and fine chemicals [1][2][3][4][5][6][7][8]. Catalysis is one of the fundamental pillars of green chemistry, the design of chemical products and processes that reduce or eliminate the use and generation of hazardous substances, as well as increase the atom economy of the reac-tion [9].…”