Mechanism and Regioselectivity of C–N Bond Cleavage and Ring Expansion of N-Heterocyclic Carbenes

2013 ◽  
Vol 33 (1) ◽  
pp. 53-60 ◽  
Author(s):  
Ran Fang ◽  
Lizi Yang ◽  
Qiang Wang
Keyword(s):  
Bond Cleavage ◽  
Ring Expansion ◽  
Heterocyclic Carbenes

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

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.

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.

25 years of N-heterocyclic carbenes: activation of both main-group element–element bonds and NHCs themselves

2016 ◽  
Vol 45 (14) ◽  
pp. 5880-5895 ◽  
Author(s):  
Sabrina Würtemberger-Pietsch ◽  
Udo Radius ◽  
Todd B. Marder
Keyword(s):  
Ring Expansion ◽  
Main Group ◽  
Heterocyclic Carbenes ◽  
Group Element ◽  
Main Group Element ◽  
The 1960S

Expanding the belt! NHC ring expansion reactions and E–E activation from the 1960s till the present are summarized.

Visible Light-Promoted Metal-Free Reduction of Organohalides by 2-Naphthyl or 2-Hydroxynaphthyl-Substituted 1,3-Dimethylbenzimidazolines

2015 ◽  
Vol 68 (11) ◽  
pp. 1648 ◽  
Author(s):  
Eietsu Hasegawa ◽  
Kazuma Mori ◽  
Shiori Tsuji ◽  
Kazuki Nemoto ◽  
Taku Ohta ◽  
...  
Keyword(s):  
Visible Light ◽  
Halogen Bond ◽  
Light Emitting Diode ◽  
Bond Cleavage ◽  
Ring Expansion ◽  
Single Electron Transfer ◽  
Reduction Reactions ◽  
Light Emitting ◽  
Reducing Ability ◽  
Carbon Radicals

The visible light-promoted reduction reactions of some organohalides were investigated using 2-aryl-1,3-dimethylbenzimidazolines (Ar-DMBIH) possessing 2-naphthyl or 2-hydroxynaphthyl substituents. In these reduction reactions, single-electron transfer from photo-excited Ar-DMBIH, attained by Xe lamp irradiation through an appropriate glass-filter (λ > 390 nm), to the halide substrates leads to the carbon–halogen bond cleavage, followed by the rearrangements of the formed carbon radicals such as 5-exo hexenyl cyclization and the Dowd–Beckwith ring expansion. Addition of 1,8-diazabicyclo[5.4.0]undec-7-ene was found to enhance the reducing ability of hydroxynaphthyl-substituted DMBIH. A household white light-emitting diode was also used as a light source for these reactions.

scholarly journals Electrochemical Ring Expansion to Synthesize Medium-Sized Lactams Through C–C Bond Cleavage

CCS Chemistry ◽  
2020 ◽  
pp. 2233-2244
Author(s):  
Kun Liu ◽  
Chunlan Song ◽  
Xu Jiang ◽  
Xin Dong ◽  
Yuqi Deng ◽  
...  
Keyword(s):  
Bond Cleavage ◽  
Ring Expansion
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