Room Temperature Ring Expansion of N-Heterocyclic Carbenes and BB Bond Cleavage of Diboron(4) Compounds

2015 ◽  
Vol 21 (25) ◽  
pp. 9018-9021 ◽  
Author(s):  
Sabrina Pietsch ◽  
Ursula Paul ◽  
Ian A. Cade ◽  
Michael J. Ingleson ◽  
Udo Radius ◽  
...  
Keyword(s):  
Room Temperature ◽  
Bond Cleavage ◽  
Ring Expansion ◽  
Heterocyclic Carbenes

CN Bond Cleavage and Ring Expansion of N-Heterocyclic Carbenes using Hydrosilanes

2012 ◽  
Vol 51 (35) ◽  
pp. 8881-8885 ◽  
Author(s):  
David Schmidt ◽  
Johannes H. J. Berthel ◽  
Sabrina Pietsch ◽  
Udo Radius
Keyword(s):  
Bond Cleavage ◽  
Ring Expansion ◽  
Heterocyclic Carbenes

Room Temperature Alkali Metal Reduction of Carbon Dioxide

2020 ◽  
Author(s):  
Lucas A. Freeman ◽  
Akachukwu D. Obi ◽  
Haleigh R. Machost ◽  
Andrew Molino ◽  
Asa W. Nichols ◽  
...  
Keyword(s):  
Alkali Metal ◽  
Alkali Metals ◽  
Room Temperature ◽  
Chemical Reduction ◽  
Bond Cleavage ◽  
Open Shell ◽  
Metal Reduction ◽  
One Pot ◽  
Earth Abundant ◽  
Electron Reduction

The reduction of the relatively inert carbon–oxygen bonds of CO<sub>2</sub> to access useful CO<sub>2</sub>-derived organic products is one of the most important fundamental challenges in synthetic chemistry. Facilitating this bond-cleavage using earth-abundant, non-toxic main group elements (MGEs) is especially arduous because of the difficulty in achieving strong inner-sphere interactions between CO<sub>2</sub> and the MGE. Herein we report the first successful chemical reduction of CO<sub>2</sub> at room temperature by alkali metals, promoted by a cyclic(alkyl)(amino) carbene (CAAC). One-electron reduction of CAAC-CO<sub>2</sub> adduct (<b>1</b>) with lithium, sodium or potassium metal yields stable monoanionic radicals clusters [M(CAAC–CO<sub>2</sub>)]<sub>n</sub>(M = Li, Na, K, <b> 2</b>-<b>4</b>) and two-electron alkali metal reduction affords open-shell, dianionic clusters of the general formula [M<sub>2</sub>(CAAC–CO<sub>2</sub>)]<sub>n </sub>(<b>5</b>-<b>8</b>). It is notable that these crystalline clusters of reduced CO<sub>2</sub> may also be isolated via the “one-pot” reaction of free CO<sub>2</sub> with free CAAC followed by the addition of alkali metals – a reductive process which does not occur in the absence of carbene. Each of the products <b>2</b>-<b>8</b> were investigated using a combination of experimental and theoretical methods.<br>

Synthesis of 2,3-dihydroquinazolinones and quinazolin-4(3H)-ones catalyzed by graphene oxide nanosheets in an aqueous medium: “on-water” synthesis accompanied by carbocatalysis and selective C–C bond cleavage

RSC Advances ◽  
2016 ◽  
Vol 6 (27) ◽  
pp. 22320-22330 ◽  
Author(s):  
Nazia Kausar ◽  
Indranil Roy ◽  
Dipankar Chattopadhyay ◽  
Asish R. Das
Keyword(s):  
Graphene Oxide ◽  
Aqueous Medium ◽  
Room Temperature ◽  
Bond Cleavage ◽  
Graphene Oxide Nanosheets ◽  
Graphene Oxide Nanosheet

Graphene oxide nanosheet catalyzed strategies for construction of 2,3-dihydroquinazolinones and quinazolin-4(3H)-ones starting from anthranilamide and an aldehyde/ketone in aqueous medium at room temperature have been realized.

Photocatalytic Chemoselective C–C Bond Cleavage at Room Temperature in Dye-Sensitized Photoelectrochemical Cells

ACS Catalysis ◽  
2021 ◽  
pp. 3771-3781
Author(s):  
Shuya Li ◽  
Saerona Kim ◽  
Andrew H. Davis ◽  
Jingshun Zhuang ◽  
Eric Wolfgang Shuler ◽  
...  
Keyword(s):  
Room Temperature ◽  
Bond Cleavage ◽  
Photoelectrochemical Cells ◽  
Dye Sensitized

Theoretical study of the mechanism for the sequential N–O and N–N bond cleavage within N2O adducts of N-heterocyclic carbenes by a vanadium(iii) complex

2016 ◽  
Vol 45 (3) ◽  
pp. 1047-1054 ◽  
Author(s):  
Robert Robinson ◽  
Miranda F. Shaw ◽  
Robert Stranger ◽  
Brian F. Yates
Keyword(s):  
Theoretical Study ◽  
Bond Cleavage ◽  
Heterocyclic Carbenes

The addition of N-heterocyclic carbene (NHC) increases the activity of N2O towards cleavage of both the N–O and N–N bonds.

The Chemical Evolution of a Nitrogenase Model, 20 Alkyl Molybdates(VI) and the Mechanism of Hydrocarbon Production by Nitrogenase [1]

1982 ◽  
Vol 37 (3) ◽  
pp. 380-385 ◽  
Author(s):  
G. N. Schrauzer ◽  
Laura A. Hughes ◽  
Norman Strampach
Keyword(s):  
Aqueous Solution ◽  
Alkaline Hydrolysis ◽  
Room Temperature ◽  
Bond Cleavage ◽  
Model Compounds ◽  
Hydrocarbon Production ◽  
Acidic Solutions ◽  
Reducing Conditions ◽  
Hydrolysis Of ◽  
Derivatives Of

Abstract Colorless alkylmolybdates(VI) of composition R-MoO3-are generated in aqueous solutions by the alkaline hydrolysis of complexes R-Mo(Bpy)(0)2Br(Bpy = 2,2′-bipyridyl, R = CH3 and higher alkyl). At room temperature in alkaline aqueous solution, the new organometallic derivatives of oxomolybdate(VI) are remarkably resistant against Mo-C bond hydrolysis. Decomposition occurs more rapidly on heating, affording unrearranged alkanes according to the eq.: R-MoO3- + OH-→RH + Mo04=. In acidic solutions, the methylmolybdate(VI) species decomposes with the formation of a mixture of methane and ethane while higher alkylmolybdates carrying hydrogen in the β-position relative to molybdenum undergo Mo-C bond heterolysis by way of β-elimina-tion: R-CH2CH2-MoO3 → Mo+4 (aq) + H+ + R-CH = CH2. The Mo-C bond of alkylmolybdates is resistant to oxidants but is very sensitive to cleavage under reducing conditions. Reductive Mo-C bond cleavage occurs particularly rapidly in the presence of thiols and reduced ferredoxin model compounds. The latter reactions simulate the terminal steps of hydrocarbon producing reactions of nitrogenase with alternate substrates such as CN-, R-CN or R-NC, confirming previous mechanistic conclusions concerning the mechanism of nitrogenase action.

Theoretical Investigation of Main-Group Element Hydride Insertion into Phosphorus-Heterocyclic Carbenes (PHCs)

2020 ◽  
Vol 73 (8) ◽  
pp. 787
Author(s):  
Khalidah H. M. Al Furaiji ◽  
Andrew Molino ◽  
Jason L. Dutton ◽  
David J. D. Wilson
Keyword(s):  
Computational Study ◽  
Ring Expansion ◽  
Heterocyclic Ring ◽  
Main Group ◽  
Heterocyclic Carbenes ◽  
Group Element ◽  
Steric Effects ◽  
Main Group Element ◽  
Theoretical Investigations ◽  
Electronic And Steric Effects

Initial reports of ring expansion reactions (RER) of N-heterocyclic carbenes (NHCs) with main-group element hydrides have led to several synthetic and theoretical investigations, which include reports of insertion by Be, B, Al, Si, and Zn hydrides. The RERs generally lead to insertion of the heteroatom into the endocyclic C–N bond with formation of an expanded heterocyclic ring. Following the recent isolation of a P-heterocyclic carbene (PHC), here we report results from a computational study (RI-SCS-MP2/def2-TZVP//M06–2X/def2-TZVP) of RERs with a series of PHCs for the ring-insertion of silicon (SiH4, SiH2Ph2) and boron (BH3, BH2NMe2) hydrides. In order to explore the roles of both electronic and steric effects on PHCs and their reactivity, a series of P-substituent PHCR (R=H, Me, Ph, and bulky Ar groups) were investigated. Bulky R groups serve to maximise ring planarity and the σ-donating capability of the PHC. For RER, the PHC analogues exhibit facile initial hydride transfer from the main-group hydrides to the carbene carbon, with barriers that are substantially lower than with NHCs. However, the full ring insertion mechanisms for PHCs are, in general, kinetically unfavourable due to a large barrier associated with the ring-expansion step. While bulky P-substituents maximise heterocycle planarity towards that of NHCs, the RER reactivity with bulky PHCs does not reflect that of an NHC.

Base induced C–CN bond cleavage at room temperature: a convenient method for the activation of acetonitrile

2019 ◽  
Vol 6 (5) ◽  
pp. 1135-1140 ◽  
Author(s):  
Xiaofeng Zhang ◽  
Zilong Zhang ◽  
Shiqun Xiang ◽  
Yingzu Zhu ◽  
Changneng Chen ◽  
...  
Keyword(s):  
Convenient Method ◽  
Room Temperature ◽  
Bond Cleavage

Acetonitrile was activated to form formaldehyde and cyanide in air. Utilization of the product [CuII–CN] for catalytic cyanation was investigated.

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