Methides iminoquinone

If an even broader definition of a Michael reaction is used, iminoquinones (19), quinone iminium ions (20), quinone methides (21), etc. can also be viewed as Michael... 

Lai WG, Zahid N, Uetrecht JP. Metabolism of trimethoprim to a reactive iminoquinone methide by activated human neutrophils and hepatic microsomes. J Pharmacol Exp Ther 1999 291(1) 292 299. 

Mewies, M., Basran, J., Packman, L. C., Hille, R., and Scrutton, N. S., 1997, Involvement of a flavin iminoquinone methide in the formation of 6- hydroxyflavin mononucleotide in trimethylamine dehydrogenase a rationale for the existence of 8a-methyl and C6-linked covalent flavoproteins. Biochemistry 36 716297168. 

Flash vacuum pyrolysis of (89) at 650 °C affords a 5% yield of oxazocine (90) (Scheme 20), resulting from dehydration to the iminoquinone methide followed by intramolecular Diels-Alder cycloaddition use of SiOj as a catalyst for the pyrolysis affords a higher yield of (90) (20%) at lower temperature (425 °C) <84tl5435>. 

Aryl substituents also activate benzyHc C-H bonds adjacent to a nitrene center. An interesting study on this topic has dealt with the atropoisomeric 3,5-dimethyl-2-(9-fluorenyl)phenylazides 49 and 52. ° The low-temperature photochemistry (77 K) of these rotameric azides proved to be fundamentally different Photolysis of 49 resulted in the formation of nitrene 50 in addition to azanorcaradiene 51, while photolysis of 52 gave nitrene 53 in addition to iminoquinone methide 54. This subsequently underwent intramolecular cycloaddition to yield dihydroindenocridine 55. Laser flash photolysis showed that the formation of iminoquinone methide 54 from azide 52 occurred in less than 10 ns. Deuteration of the 9-position of the fluorene chromophore resulted in a significantly diminished yield of 55. LFP of the rotameric azide 49 yielded the rate constant for the formation of azanorcaradiene 51 which was determined as k = 7.1 x 10 ... 

Bucher, G., Photochemical generation of iminoquinone methides by 1,4-hydrogen migration in derivatives of o-tolylnitrene, Enr. /. Org. Chem., 2447, 2001. 

Bucher, G., A laser flash photolj is study on 2-azido-N,N-diethylbenzylamine the reactivity of iminoquinone methides in solution, Eur.. Org. Chem., 2463, 2001. 

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