1,3-Dipolar Cycloaddition with Diazo Groups: Noncovalent Interactions Overwhelm Strain.
Like azides, diazoacetamides undergo 1,3-dipolar cycloadditions with oxanorbornadienes (OND) in a reaction that is accelerated by the relief of strain in the transition state. The cycloaddition of a diazoacetamide with unstrained ethyl 4,4,4-trifluoro-2-butynoate is, however, 35-fold faster than with the analogous OND because of favorable interactions with the fluoro groups. Its rate constant (k = 0.53 M(-1) s(-1) in methanol) is comparable to those of strain-promoted azide-cyclooctyne cycloadditions.
Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin, 53706, United States.
Brian
B
Gold
Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin, 53706, United States.
Matthew R
MR
Aronoff
Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin, 53706, United States.|Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, 53706, United States.
Ronald T
RT
Raines
D000081:Acetamides / Q000737:chemistry; D001386:Azides / Q000737:chemistry; D002087:Butyrates / Q000737:chemistry; D061565:Cycloaddition Reaction; D007700:Kinetics; D000432:Methanol / Q000737:chemistry; D011720:Pyrazoles / Q000138:chemical synthesis*; D011789:Quantum Theory; D012997:Solvents / Q000737:chemistry
D000081:Acetamides; D001386:Azides; D002087:Butyrates; D011720:Pyrazoles; D012997:Solvents; D000432:Methanol