Electrostatic interactions between substituents as regioselectivity control elements in Diels-Alder cycloadditions. A DFT study of cycloadditions of 1-methoxy-4-trimethylsiloxy dienes with acrylonitrile

Gregori Ujaque, Joseph E. Norton, K. N. Houk*

*Corresponding author for this work

Research output: Contribution to journalArticleResearchpeer-review

18 Citations (Scopus)

Abstract

The regioselectivities of Diels-Alder reactions of 1-methoxy-4-trimethylsiloxy-1,3-butadiene and the corresponding o-xylylene with acrylonitrile were explored with density functional theory. The transition state of the reaction of the diene with acrylonitrile was studied in both the gas phase and in a low dielectric (ε = 2.247) solvent. The regioselectivities of these reactions are predicted to be controlled by the direct electrostatic interactions between the diene and dienophile substituents. The electron-donating capacities of methoxy and trimethylsiloxy substituents are shown to be very similar and to not contribute to regioselectivity control. A prediction is made that the cycloadditions of the o-xylylene will be unselective, while 1-methoxy-4-trimethylsiloxy-1,3-butadiene will give a small preference (∼5:1) in favor of the proximal methoxy and cyano groups. The thermochromic behavior of trans-disubstituted disiloxy benzocyclobutene was also explored.

Original languageEnglish
Pages (from-to)7179-7184
Number of pages6
JournalJournal of Organic Chemistry
Volume67
Issue number21
DOIs
Publication statusPublished - 18 Oct 2002

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