Carbene reactivity of 4-diazo-4H-imidazoles toward nucleophiles and aromatic compounds.
Carbenes derived from diazoimidazolecarboxylates 4 under thermal or photochemical conditions undergo O-H and N-H insertion reactions with alcohols and amines, respectively, in moderate yield, in competition with reduction in good H-donor solvents. Dichloromethane reacts to give the corresponding 4-chloroimidazole. Aromatic hydrocarbons are excellent traps for the imidazolylidene carbene and lead to a range of arylimidazole derivatives 7. Reaction with pyridine leads to the first example of a pyridinium ylide 8 formed from an imidazolylidene carbene, whereas irradiation in hexafluorobenzene gives the imidazoazocine 11, presumably by way of an initial norcaradiene intermediate.
Smith
Matthew R
MR
School of Chemistry, University of Nottingham, University Park, NottinghamNG7 2RD, UK.
Blake
Alexander J
AJ
Hayes
Christopher J
CJ
Stevens
Malcolm F G
MF
Moody
Christopher J
CJ
D000438:Alcohols / Q000737:chemistry; D000588:Amines / Q000737:chemistry; D000970:Antineoplastic Agents / Q000737:chemistry; D001391:Azo Compounds / Q000737:chemistry*; D003500:Cyclization; D005466:Fluorocarbons / Q000737:chemistry; D006841:Hydrocarbons, Aromatic / Q000737:chemistry*; D006859:Hydrogen / Q000737:chemistry; D007093:Imidazoles / Q000737:chemistry*; D008697:Methane / Q000031:analogs & derivatives* / Q000737:chemistry; D009584:Nitrogen / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry; D010777:Photochemistry; D011725:Pyridines / Q000737:chemistry; D012997:Solvents / Q000737:chemistry; D013696:Temperature
D000438:Alcohols; D000588:Amines; D000970:Antineoplastic Agents; D001391:Azo Compounds; D005466:Fluorocarbons; D006841:Hydrocarbons, Aromatic; D007093:Imidazoles; D011725:Pyridines; D012997:Solvents; C030011:carbene; D006859:Hydrogen; C003005:hexafluorobenzene; D009584:Nitrogen; C023666:pyridine; D008697:Methane; D010100:Oxygen