Cyclic 1,3-dipoles or acyclic phosphonium ylides? Electronic characterization of "montrealones"

Krenske, Elizabeth H., Houk, K. N., Arndtsen, Bruce A. and St. Cyr, Daniel J. (2008) Cyclic 1,3-dipoles or acyclic phosphonium ylides? Electronic characterization of "montrealones". Journal of the American Chemical Society, 130 31: 10052-10052. doi:10.1021/ja802646f


Author Krenske, Elizabeth H.
Houk, K. N.
Arndtsen, Bruce A.
St. Cyr, Daniel J.
Title Cyclic 1,3-dipoles or acyclic phosphonium ylides? Electronic characterization of "montrealones"
Journal name Journal of the American Chemical Society   Check publisher's open access policy
ISSN 0002-7863
1520-5126
Publication date 2008-08
Sub-type Article (original research)
DOI 10.1021/ja802646f
Volume 130
Issue 31
Start page 10052
End page 10052
Total pages 2
Place of publication Washington, United States
Publisher American Chemical Society
Language eng
Formatted abstract
The structural features of a recently introduced class of 1,3-dipolar reagents have been computed by density functional theory and ab initio methods. The reagents are formally derived from Münchnones by replacement of the C═O group with a PR3 unit. The parent species (PR3 = PH3) shows a long P···O interaction (2.55 Å at the B3LYP/6-31+G(d) level), together with a nonplanar ring, and is best described as a weakly chelated acylamino-phosphonium ylide. The corresponding acyclic form, in which the P···O interaction is absent, is predicted to be 2−3 kcal mol−1 higher in enthalpy. Variation of the phosphorus substituents exerts a marked effect on the P···O distance, with electron-withdrawing groups favoring a covalent interaction [P···O 1.97 Å for PR3 = PPh(catechyl)] and electron-donating groups favoring a weak interaction [P···O 3.92 Å for PR3 = PPh3]. However, this variation has little effect on the relative energies of the cyclic and acyclic forms. The barriers for concerted cycloadditions with ethylene are 22.8 kcal mol−1 (PH3), 31.7 kcal mol−1 (PPh3), and 16.2 kcal mol−1 [PPh(catechyl) with axial O], which correspond with experimental observations and follow the same trend as the energies required to distort the dipole to the TS geometry.
Keyword Derivatives
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Chemistry and Molecular Biosciences
 
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