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Inter ­ action between maleic acid and N - R -furfuryl ­ amines: crystal structure of 2-methyl- N -[(5-phenyl ­ furan-2-yl)meth ­ yl]propan-2-aminium (2 Z )-3-carb ­ oxy ­ acrylate and N -[(5-iodo ­ furan-2-yl)meth ­ yl]-2-methyl ­ propan-2-aminium (2 Z )-3-carb ­ oxy ­ prop-2-enoate

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ABSTRACT

The title mol­ecular salts, C15H20NO+·C4H3O4−, (I), and C9H15INO+·C4H3O4−, (II), have very similar mol­ecular geometries for both cation and anion. The anions of both (I) and (II) are practically planar (r.m.s. deviations = 0.062 and 0.072 Å, respectively) and adopt a rare symmetrical geometry with the hy­droxy H atom approximately equidistant from the two O atoms. In their crystals, the cations and anions in both (I) and (II) form tight ionic pairs via strong N—H⋯O hydrogen bonds, with a roughly perpendicular disposition of the anion to the furan ring of the cation. This ion-pair conformation appears to correlate with the lack of reactivity of these salts in [4 + 2] cyclo­addition reactions. In the extended structures of (I) and (II), the ion pairs form hydrogen-bonded chains propagating along [010] and [001], respectively, via N—H⋯O hydrogen bonds.

No MeSH data available.


The attempted thermal cyclization of salts (I) (R = Ph) and (II) (R = I).
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fig2: The attempted thermal cyclization of salts (I) (R = Ph) and (II) (R = I).

Mentions: The main goal of this work was to study the cyclo­addition reaction between 5-R-furfuryl-tert-butyl­amines and maleic acid. The inter­action between the corresponding amines and maleic acid at room temperature leads to the salts (I) and (II) only (Fig. 1 ▸). Unexpectedly, attempts to achieve thermal cyclization of salts (I) and (II) did not result in isolation of the targeted 7-oxabi­cyclo­[2.2.1]heptenes: the initial maleates remained unchanged at temperatures up to 413 K (Fig. 2 ▸). In order to explain this fact by an understanding of their stereochemical features, an X-ray diffraction study of compounds (I) and (II) was undertaken.


Inter ­ action between maleic acid and N - R -furfuryl ­ amines: crystal structure of 2-methyl- N -[(5-phenyl ­ furan-2-yl)meth ­ yl]propan-2-aminium (2 Z )-3-carb ­ oxy ­ acrylate and N -[(5-iodo ­ furan-2-yl)meth ­ yl]-2-methyl ­ propan-2-aminium (2 Z )-3-carb ­ oxy ­ prop-2-enoate
The attempted thermal cyclization of salts (I) (R = Ph) and (II) (R = I).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5382611&req=5

fig2: The attempted thermal cyclization of salts (I) (R = Ph) and (II) (R = I).
Mentions: The main goal of this work was to study the cyclo­addition reaction between 5-R-furfuryl-tert-butyl­amines and maleic acid. The inter­action between the corresponding amines and maleic acid at room temperature leads to the salts (I) and (II) only (Fig. 1 ▸). Unexpectedly, attempts to achieve thermal cyclization of salts (I) and (II) did not result in isolation of the targeted 7-oxabi­cyclo­[2.2.1]heptenes: the initial maleates remained unchanged at temperatures up to 413 K (Fig. 2 ▸). In order to explain this fact by an understanding of their stereochemical features, an X-ray diffraction study of compounds (I) and (II) was undertaken.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

The title mol­ecular salts, C15H20NO+·C4H3O4−, (I), and C9H15INO+·C4H3O4−, (II), have very similar mol­ecular geometries for both cation and anion. The anions of both (I) and (II) are practically planar (r.m.s. deviations = 0.062 and 0.072 Å, respectively) and adopt a rare symmetrical geometry with the hy­droxy H atom approximately equidistant from the two O atoms. In their crystals, the cations and anions in both (I) and (II) form tight ionic pairs via strong N—H⋯O hydrogen bonds, with a roughly perpendicular disposition of the anion to the furan ring of the cation. This ion-pair conformation appears to correlate with the lack of reactivity of these salts in [4 + 2] cyclo­addition reactions. In the extended structures of (I) and (II), the ion pairs form hydrogen-bonded chains propagating along [010] and [001], respectively, via N—H⋯O hydrogen bonds.

No MeSH data available.