title: Synthesis and computational analysis of densely functionalized triazoles using o-nitrophenylalkynes.
abstract: Dipolar cylcoadditions with azides using a series of o-nitrophenylethynes and disubstituted alkynes were studied experimentally and computationally. Density functional theory computations reveal the steric and electronic parameters that control the regioselectivity of these cycloadditions. Several new substrates were predicted that would either give enhanced regiocontrol or invert the regiochemical preference. Experimentally, the alkynes were screened in the [3 + 2] cycloaddition with benzyl azide. Of the 11 alkynes screened experimentally, the acetylenes containing halogen substitution directly on the alkyne provided the highest levels of regioselectivity. These haloalkynes were also shown to tolerate variation of the azide moiety with continued good levels of regioselectivity in most cases. Diverse functional groups can be incorporated through the cycloaddition process and their subsequent orthogonal modification was demonstrated.
authors.affiliation: Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon 97331, USA.
authors.forename: Melissa L
authors.initials: ML
authors.lastname: McIntosh
authors.forename: Ryne C
authors.initials: RC
authors.lastname: Johnston
authors.forename: Ommidala
authors.initials: O
authors.lastname: Pattawong
authors.forename: Bradley O
authors.initials: BO
authors.lastname: Ashburn
authors.forename: Michael R
authors.initials: MR
authors.lastname: Naffziger
authors.forename: Paul Ha-Yeon
authors.initials: PH
authors.lastname: Cheong
authors.forename: Rich G
authors.initials: RG
authors.lastname: Carter