Details
| Original language | English |
|---|---|
| Pages (from-to) | 10214-10219 |
| Number of pages | 6 |
| Journal | Chemistry - a European journal |
| Volume | 16 |
| Issue number | 33 |
| Publication status | Published - 3 Sept 2010 |
Abstract
The conformational landscape of the alkaloid anabasine (neonicotine) has been investigated by using rotational spectroscopy and ab initio calculations. The results allow a detailed comparison of the structural properties of the prototype piperidinic and pyrrolidinic nicotinoids (anabasine vs. nicotine). Anabasine adopts two most stable conformations in isolation conditions, for which we determined accurate rotational and nuclear quadrupole coupling parameters. The preferred conformations are characterized by an equatorial pyridine moiety and additional N-H equatorial stereochemistry at the piperidine ring (eq-eq; eq= equatorial). The two rings of anabasine are close to a bisecting arrangement, with the observed conformations differing by an approximately 1808 rotation of the pyridine subunit, denoted either syn or anti. The preference of anabasine for the eq-eq-syn conformation has been established by relative intensity measurements (syn/anti ∼ 5(2)). The conformational preferences of free anabasine are directed by a weak N···H C hydrogen bond interaction between the nitrogen lone pair at piperidine and the closest C-H bond in pyridine, with N···H distances ranging from 2.686 (syn) to 2.667 Å (anti). Supporting ab initio calculations by using MP2 and the recent M05-2X density functional are provided, evaluating the predictive performance of both methods.
Keywords
- Alkaloids, Conformation analysis, Nicotinoids, Rotational spectroscopy, Stereochemistry
ASJC Scopus subject areas
- Chemical Engineering(all)
- Catalysis
- Chemistry(all)
- Organic Chemistry
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In: Chemistry - a European journal, Vol. 16, No. 33, 03.09.2010, p. 10214-10219.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - The conformational landscape of nicotinoids
T2 - Solving the conformational disparity of anabasine
AU - Lesarri, Alberto
AU - Cocinero, Emilio J.
AU - Evangelisti, Luca
AU - Suenram, Richard D.
AU - Caminati, Walther
AU - Grabow, Jens Uwe
PY - 2010/9/3
Y1 - 2010/9/3
N2 - The conformational landscape of the alkaloid anabasine (neonicotine) has been investigated by using rotational spectroscopy and ab initio calculations. The results allow a detailed comparison of the structural properties of the prototype piperidinic and pyrrolidinic nicotinoids (anabasine vs. nicotine). Anabasine adopts two most stable conformations in isolation conditions, for which we determined accurate rotational and nuclear quadrupole coupling parameters. The preferred conformations are characterized by an equatorial pyridine moiety and additional N-H equatorial stereochemistry at the piperidine ring (eq-eq; eq= equatorial). The two rings of anabasine are close to a bisecting arrangement, with the observed conformations differing by an approximately 1808 rotation of the pyridine subunit, denoted either syn or anti. The preference of anabasine for the eq-eq-syn conformation has been established by relative intensity measurements (syn/anti ∼ 5(2)). The conformational preferences of free anabasine are directed by a weak N···H C hydrogen bond interaction between the nitrogen lone pair at piperidine and the closest C-H bond in pyridine, with N···H distances ranging from 2.686 (syn) to 2.667 Å (anti). Supporting ab initio calculations by using MP2 and the recent M05-2X density functional are provided, evaluating the predictive performance of both methods.
AB - The conformational landscape of the alkaloid anabasine (neonicotine) has been investigated by using rotational spectroscopy and ab initio calculations. The results allow a detailed comparison of the structural properties of the prototype piperidinic and pyrrolidinic nicotinoids (anabasine vs. nicotine). Anabasine adopts two most stable conformations in isolation conditions, for which we determined accurate rotational and nuclear quadrupole coupling parameters. The preferred conformations are characterized by an equatorial pyridine moiety and additional N-H equatorial stereochemistry at the piperidine ring (eq-eq; eq= equatorial). The two rings of anabasine are close to a bisecting arrangement, with the observed conformations differing by an approximately 1808 rotation of the pyridine subunit, denoted either syn or anti. The preference of anabasine for the eq-eq-syn conformation has been established by relative intensity measurements (syn/anti ∼ 5(2)). The conformational preferences of free anabasine are directed by a weak N···H C hydrogen bond interaction between the nitrogen lone pair at piperidine and the closest C-H bond in pyridine, with N···H distances ranging from 2.686 (syn) to 2.667 Å (anti). Supporting ab initio calculations by using MP2 and the recent M05-2X density functional are provided, evaluating the predictive performance of both methods.
KW - Alkaloids
KW - Conformation analysis
KW - Nicotinoids
KW - Rotational spectroscopy
KW - Stereochemistry
UR - http://www.scopus.com/inward/record.url?scp=77956096308&partnerID=8YFLogxK
U2 - 10.1002/chem.201000849
DO - 10.1002/chem.201000849
M3 - Article
C2 - 20623731
AN - SCOPUS:77956096308
VL - 16
SP - 10214
EP - 10219
JO - Chemistry - a European journal
JF - Chemistry - a European journal
SN - 0947-6539
IS - 33
ER -