Highly chemoselective hydroelementation of diverse terminal alkenes catalyzed by readily available platinum complexes bearing P,N-donor ligands is reported. The developed approach enables ...comprehensive incorporation of silyl-, germyl-, and boryl-moieties at remarkably low catalyst concentrations. Consequently, 47 products were efficiently synthesized, showcasing exclusive modification of terminal C=C moieties in the presence of various sensitive groups, e.g. internal CC, CO, or OH.
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•Novel Pt(II) complexes with easily accessible bidentate P,N-donor ligands.•High catalytic activity in diverse hydroelementations.•Exclusive modification of terminal CC bonds in multifunctional compounds.•Reusable catalyst maintains activity and chemoselectivity over multiple cycles.•Applicability to various synthetic domains, including natural products and POSS.
In this report, we present the synthesis of six novel neutral platinum complexes employing readily available P,N-donor ligands through a straightforward two-step procedure. Subsequently, we investigated their catalytic activity in the hydroelementation of terminal olefins, highlighting their versatile utility in material and natural product chemistry. The efficient addition of silicon, germanium, and boron hydrides to the CC bond at low catalyst loading occurred exclusively in an anti-Markovnikov manner. Furthermore, our substrate scope encompasses a wide range of aliphatic and aromatic alkenes, featuring substituents with varying electronic properties. In contrast to many previous Pt-complexes, our catalytic system displayed exceptional chemoselectivity towards other unsaturated functional groups, such as carbonyl and internal CC bonds. Notably, it also exhibited remarkable tolerance to hydroxyl, alkoxyl, silyl, and thioether moieties. Additionally, we accentuated the prowess of our catalyst, showcasing its capability to sustain consistent activity and selectivity throughout numerous catalytic cycles.
An expeditious synthesis of an advanced tripeptide intermediate en route to a tubulysin antibody–drug conjugate payload is described. The efficient formation of an N-propyl tertiary amide required ...tailoring the amine component to reduce steric demand. Additionally, double activation of the carboxylate was required via an aluminum–Lewis acid coupled activated ester strategy to enable the formation of the highly congested amide bond with superior retention of stereochemical integrity. Other permutations of reactant structure and reagents met with failure. The realization of this key direct bond construction enabled a convergent solution-phase synthesis of the unnatural tubulysin tripeptide in a highly convergent manner from three simple building blocks in eight steps and 22.4% overall yield utilizing only a single silica gel chromatographic purification.
This review covers the advance in the development of Fe, Co, and Ni catalysts for the alkene hydrosilylation reaction, as well as the related dehydrogenative silylation reaction. The hydrosilylation ...of alkene is an important reaction for the synthesis of alkylsilanes that has widespread applications in numerous silicon-based materials, and for decades, this transformation has been relying on the use of Pt catalysts. Recently, the high abundance and low cost, coupled with the environmentally benign nature of the base metals have stimulated enormous research on the development of first-row transition-metal catalysts as replacements for the precious Pt catalysts. Several base-metal catalysts which have emerged during the past 5 years offer high activity, broad substrate scope, and excellent regioselectivity. Both of the anti-Markovnikov and the unusual Markovnikov additions can be achieved in a high degree of regioselectivity. The reactions of acyclic internal olefins catalyzed by the base-metal catalysts reported to date yield linear alkylsilanes via a tandem olefin-isomerization and hydrosilylation process. A few catalysts enable the dehydrogenative silylation of alkenes to form vinylsilanes and/or allylsilanes.
The demand for economical and environmentally benign catalysts for important chemical transformations has recently initiated great efforts on nonprecious metal-catalyzed hydrosilylation reactions. ...The special chemical properties of cobalt enable the development of diverse cobalt complex-based catalysts for hydrosilylation reactions. This paper reviews the significant advances of cobalt complex-catalyzed hydrosilylation of alkenes and alkynes from the early studies in the 1960s until now, with the objective of providing readers with the status of the field and the underlying late 3d metal chemistry that is meaningful for new nonprecious metal catalyst design. Progress, problems, and perspectives in this vibrant field are discussed.
We report an enantioselective cobalt‐catalyzed hydrosilylation/cyclization reaction of 1,6‐enynes with secondary and tertiary hydrosilanes employing a catalyst generated in situ from the combination ...of Co(acac)2 and (R,Sp)‐Josiphos. A wide range of oxygen‐, nitrogen‐, and carbon‐tethered 1,6‐enynes reacted with Ph2SiH2, (EtO)3SiH, or (RO)2MeSiH to afford the corresponding chiral organosilane products in high yields and up to >99 % ee. This cobalt‐catalyzed hydrosilylation/cyclization also occurred with prochiral secondary hydrosilane PhMeSiH2 to yield chiral alkylsilanes containing both carbon‐ and silicon‐stereogenic centers with excellent enantioselectivity, albeit with modest diastereoselectivity. The chiral organosilane products from this cobalt‐catalyzed asymmetric hydrosilylation/cyclization could be converted to a variety of chiral five‐membered heterocyclic compounds by stereospecific conversion of their C−Si and Si−H bonds without loss of enantiopurity.
Enantioselective cobalt‐catalyzed hydrosilylation/cyclization of 1,6‐enynes is developed to access synthetically versatile chiral alkylsilanes with a catalyst generated in situ from Co(acac)2 and (R,Sp)‐Josiphos. A wide range of 1,6‐enynes react to afford the corresponding alkylsilanes in good yields with excellent enantioselectivity (up to >99 % ee).
Here, we report the first example of Ni‐catalyzed asymmetric hydrosilylation of 1,1‐disubstituted allenes with high level of regioselectivities and enantioselectivities. The key to achieve this ...stereoselective hydrosilylation reaction was the development of the SPSiOL‐derived bisphosphite ligands (SPSiPO). This protocol features broad substrate scope, excellent functional group, and heterocycle tolerance, thus provides a versatile method for the construction of enantioenriched tertiary allylsilanes in a straightforward and atom‐economic manner. DFT calculations were performed to reveal the reaction mechanism and the origins of the enantioselectivity.
With a newly developed SPSiOL‐base bisphosphite ligand (SPSiPO), Ni‐catalyzed asymmetric hydrosilylation of 1,1‐disubstituted allenes was realized for the first time, delivering the enantioenriched allylsilanes bearing a tertiary carbon stereocenter in high efficiency and 100 % atom‐economy with high chemo‐, regio‐ and enantioselectivities.
Catalytic hydrosilylation of various multiple bonds provides access to numerous organosilicon compounds. One of the most important applications of this reaction is asymmetric hydrosilylation of ...prochiral ketones to give silyl ethers, which can be easily hydrolyzed to chiral alcohols – important building blocks and intermediates in different fields of chemistry. Until recently its wide-spread application in synthetic chemistry was limited due to the high price and low commercial availability of the catalytic systems, as well as high substrate dependence. The present review describes the advances in the development of the homogenous catalytic systems for asymmetric hydrosilylation of prochiral ketones for the period of 2010–2020, which is characterized by significant progress in the efficiency of the catalytic systems using base metals, expansion of the substrate scope, and further improvement of reaction conditions.
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•Progress in asymmetric homogenous hydrosilylation of ketones within the period of 2010–2020 has been reviewed.•Remarkable progress in efficiency of catalytic systems and their applicability has been achieved.•Major advances can be seen in the development of catalytic systems featuring inexpensive and highly abundant metals.•Some of such catalytic systems approach or even reach the performance of state of the art rhodium-based catalysts.•After decades of basic research asymmetric hydrosilylation of ketones may become an efficient tool for synthetic chemistry.
The asymmetric reduction of 1,2‐diketones for the synthesis of optically active 1,2‐diols, especially 1,2‐anti‐diols, remains a formidable challenge. In this paper, we describe the first highly ...stereoselective hydrosilylation of unsymmetrical vicinal diketones with PhSiH3 by using a chiral frustrated Lewis pair (FLP) catalyst, giving a variety of 1,2‐diaryl‐1,2‐anti‐diols in high yields with excellent d.r. values and up to 97 % ee. The chiral FLP catalyst exhibits the ability to control regio‐, diastereo‐ and enantioselectivites concurrently.
A highly stereoselective hydrosilylation of unsymmetrical vicinal diketones with PhSiH3 was accomplished under the frustrated Lewis pair (FLP) catalysis, delivering 1,2‐di‐aryl‐1,2‐anti‐diols in high yields with >99/1 dr values and up to 97 % ee. The chiral FLP catalyst exhibits the ability to control regio‐, diastereo‐, and enantioselectivities, while silane PhSiH3 facilitates an intramolecular hydrosilylation of the second carbonyl group.
