Michael Montag | Weizmann Institute of Science (original) (raw)

Papers by Michael Montag

A key challenge in green synthesis is the catalytic transformation of renewable substrates at hig... more A key challenge in green synthesis is the catalytic transformation of renewable substrates at high atom and energy efficiency, with minimal exergonicity (∆G≈0). Non-thermal pathways, i.e., electrochemical and photochemical, can be used to leverage renewable energy resources to drive chemical processes at well-defined energy input and efficiency. Within this context, photochemical benzene carbonylation to produce benzaldehyde is a particularly interesting, albeit challenging, process that combines unfavorable thermodynamics (DG° = 1.7 kcal/mol) and the breaking of strong C-H bonds (113.5 kcal/mol) with full atom efficiency and renewable starting materials. Nevertheless, little progress has been made since this transformation was first reported, in 1980s and '90s. By following a mechanistic approach, applying spectrophotochemical and computational tools, we sought to gain a detailed understanding of the non-thermal C-H activation of benzene using metal-ligand cooperative (MLC) PNP rhodium complexes. This allowed us to unlock catalytic MLC benzene carbonylation promoted by irradiation in the near-visible UV region (390 nm) for the first time.

The Cambridge Structural Database, 2023

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Israel Journal of Chemistry, Jul 28, 2023

Pincer ligand complexes, which appeared nearly five decades ago, have provided a valuable platfor... more Pincer ligand complexes, which appeared nearly five decades ago, have provided a valuable platform for the study of fundamental chemical processes and the development of efficient catalysts for many chemical transformations. These complexes have usually contained transition metal atoms or ions, and their respective pincer ligands have often featured phosphine donor groups, which strongly coordinate to the metal center and allow its steric and electronic properties to be fine‐tuned. The increasing need to develop cost‐effective and sustainable catalytic processes has driven the search for main‐group metals as alternatives to commonly‐used transition metals. In this review, we show that despite the inherent mismatch between phosphines, which are soft Lewis bases, and main‐group metal ions, which are hard Lewis acids, a series of well‐defined phosphine‐based pincer complexes containing Li(I), Na(I), K(I), Mg(II), Ca(II), Zn(II) and Al(III) have been reported, which have proven to be active catalysts for industrially‐relevant transformations.

Pure and Applied Chemistry, Jan 30, 2023

Journal of the American Chemical Society, Jul 15, 2022

Catalytic semihydrogenation of internal alkynes using H2 is an attractive atom-economical route t... more Catalytic semihydrogenation of internal alkynes using H2 is an attractive atom-economical route to various alkenes, and its stereocontrol has received widespread attention, both in homogeneous and heterogeneous catalyses. Herein, a novel strategy is introduced, whereby a poisoning catalytic thiol is employed as a reversible inhibitor of a ruthenium catalyst, resulting in a controllable H2-based semihydrogenation of internal alkynes. Both (E)- and (Z)-alkenes were obtained efficiently and highly selectively, under very mild conditions, using a single homogeneous acridine-based ruthenium pincer catalyst. Mechanistic studies indicate that the (Z)-alkene is the reaction intermediate leading to the (E)-alkene and that the addition of a catalytic amount of bidentate thiol impedes the Z/E isomerization step by forming stable ruthenium thiol(ate) complexes, while still allowing the main hydrogenation reaction to proceed. Thus, the absence or presence of catalytic thiol controls the stereoselectivity of this alkyne semihydrogenation, affording either the (E)-isomer as the final product or halting the reaction at the (Z)-intermediate. The developed system, which is also applied to the controllable isomerization of a terminal alkene, demonstrates how metal catalysis with switchable selectivity can be achieved by reversible inhibition of the catalyst with a simple auxiliary additive.

Catalytic semihydrogenation of internal alkynes using H2 is an attractive atom-economical route t... more Catalytic semihydrogenation of internal alkynes using H2 is an attractive atom-economical route to various alkenes, and its stereocontrol has received widespread attention, both in homogeneous and heterogeneous catalysis. Herein, a novel strategy is introduced, whereby a poisoning catalytic thiol is employed as a reversible inhibitor of a ruthenium catalyst, resulting in the first controllable H2-based semihydrogenation of internal alkynes. Both (E)- and (Z)-alkenes were obtained efficiently and highly-selectively, under very mild conditions, using a single homogenous acridine-based ruthenium catalyst. Mechanistic studies indicate that the (Z)-alkene is the reaction intermediate leading to the (E)-alkene, and that addition of a catalytic amount of bidentate thiol impedes the Z-E isomerization step by forming stable ruthenium thiol(ate) complexes, while still allowing the main hydrogenation reaction to proceed. Thus, the absence or presence of catalytic thiol controls the stereoselec...

Chemical Science, 2022

The highly desirable synthesis of the widely-used primary amides directly from alcohols and ammon... more The highly desirable synthesis of the widely-used primary amides directly from alcohols and ammonia via acceptorless dehydrogenative coupling represents a clean, atom-economical, sustainable process. Nevertheless, such a reaction has not...

The Cambridge Structural Database, 2023

Israel Journal of Chemistry, Jul 28, 2023

Pure and Applied Chemistry, Jan 30, 2023

Journal of the American Chemical Society, Jul 15, 2022

Catalytic semihydrogenation of internal alkynes using H2 is an attractive atom-economical route t... more Catalytic semihydrogenation of internal alkynes using H2 is an attractive atom-economical route to various alkenes, and its stereocontrol has received widespread attention, both in homogeneous and heterogeneous catalysis. Herein, a novel strategy is introduced, whereby a poisoning catalytic thiol is employed as a reversible inhibitor of a ruthenium catalyst, resulting in the first controllable H2-based semihydrogenation of internal alkynes. Both (E)- and (Z)-alkenes were obtained efficiently and highly-selectively, under very mild conditions, using a single homogenous acridine-based ruthenium catalyst. Mechanistic studies indicate that the (Z)-alkene is the reaction intermediate leading to the (E)-alkene, and that addition of a catalytic amount of bidentate thiol impedes the Z-E isomerization step by forming stable ruthenium thiol(ate) complexes, while still allowing the main hydrogenation reaction to proceed. Thus, the absence or presence of catalytic thiol controls the stereoselec...

Chemical Science, 2022