Abstract
Irradiation of 2-benzoyladamantane derivatives in zeolites yields the endo-cyclobutanols as the only photoproduct via a γ-hydrogen abstraction process. The cyclobutanols readily undergo retroaldol reaction to give δ-ketoesters. The enantiomeric excess (ee) in the endo-cyclobutanols is measured by monitoring the ee in the ketoesters. Whereas in solution the ee in the product ketoester is zero, within achiral NaY zeolite, in the presence of a chiral inductor such as pseudoephedrine, ee's up to 28% have been obtained. The influence of zeolite on several chiral esters of 2-benzoyladamantane-2-carboxylic acids has also been examined. Whereas in solution the diastereomeric excess is <15%, in zeolite the δ-ketoesters are obtained in 79% de (best examples). Ab initio computations suggest that enhancement of chiral induction within zeolites is likely to be due to cation complexation with the reactant ketone. Alkali ion-organic interaction, a powerful tool, is waiting to be fully exploited in photochemical and thermal reactions. In this context zeolites could be a useful medium as one could view them as a reservoir of "naked" alkali ions that are only partially coordinated to the zeolite walls.
| Original language | English |
|---|---|
| Pages (from-to) | 8339-8350 |
| Number of pages | 12 |
| Journal | Journal of Organic Chemistry |
| Volume | 67 |
| Issue number | 24 |
| DOIs | |
| State | Published - Nov 29 2002 |
| Externally published | Yes |
Fingerprint
ASJC Scopus subject areas
- Organic Chemistry
Cite this
Enhanced enantio- and diastereoselectivity via confinement and cation binding : Yang photocyclization of 2-benzoyladamantane derivatives within zeolites. / Natarajan, Arunkumar; Joy, Abraham; Kaanumalle, Lakshmi S.; Scheffer, John R.; Ramamurthy, Vaidhyanathan.
In: Journal of Organic Chemistry, Vol. 67, No. 24, 29.11.2002, p. 8339-8350.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Enhanced enantio- and diastereoselectivity via confinement and cation binding
T2 - Yang photocyclization of 2-benzoyladamantane derivatives within zeolites
AU - Natarajan, Arunkumar
AU - Joy, Abraham
AU - Kaanumalle, Lakshmi S.
AU - Scheffer, John R.
AU - Ramamurthy, Vaidhyanathan
PY - 2002/11/29
Y1 - 2002/11/29
N2 - Irradiation of 2-benzoyladamantane derivatives in zeolites yields the endo-cyclobutanols as the only photoproduct via a γ-hydrogen abstraction process. The cyclobutanols readily undergo retroaldol reaction to give δ-ketoesters. The enantiomeric excess (ee) in the endo-cyclobutanols is measured by monitoring the ee in the ketoesters. Whereas in solution the ee in the product ketoester is zero, within achiral NaY zeolite, in the presence of a chiral inductor such as pseudoephedrine, ee's up to 28% have been obtained. The influence of zeolite on several chiral esters of 2-benzoyladamantane-2-carboxylic acids has also been examined. Whereas in solution the diastereomeric excess is <15%, in zeolite the δ-ketoesters are obtained in 79% de (best examples). Ab initio computations suggest that enhancement of chiral induction within zeolites is likely to be due to cation complexation with the reactant ketone. Alkali ion-organic interaction, a powerful tool, is waiting to be fully exploited in photochemical and thermal reactions. In this context zeolites could be a useful medium as one could view them as a reservoir of "naked" alkali ions that are only partially coordinated to the zeolite walls.
AB - Irradiation of 2-benzoyladamantane derivatives in zeolites yields the endo-cyclobutanols as the only photoproduct via a γ-hydrogen abstraction process. The cyclobutanols readily undergo retroaldol reaction to give δ-ketoesters. The enantiomeric excess (ee) in the endo-cyclobutanols is measured by monitoring the ee in the ketoesters. Whereas in solution the ee in the product ketoester is zero, within achiral NaY zeolite, in the presence of a chiral inductor such as pseudoephedrine, ee's up to 28% have been obtained. The influence of zeolite on several chiral esters of 2-benzoyladamantane-2-carboxylic acids has also been examined. Whereas in solution the diastereomeric excess is <15%, in zeolite the δ-ketoesters are obtained in 79% de (best examples). Ab initio computations suggest that enhancement of chiral induction within zeolites is likely to be due to cation complexation with the reactant ketone. Alkali ion-organic interaction, a powerful tool, is waiting to be fully exploited in photochemical and thermal reactions. In this context zeolites could be a useful medium as one could view them as a reservoir of "naked" alkali ions that are only partially coordinated to the zeolite walls.
UR - http://www.scopus.com/inward/record.url?scp=0037195714&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0037195714&partnerID=8YFLogxK
U2 - 10.1021/jo0260793
DO - 10.1021/jo0260793
M3 - Article
C2 - 12444610
AN - SCOPUS:0037195714
VL - 67
SP - 8339
EP - 8350
JO - Journal of Organic Chemistry
JF - Journal of Organic Chemistry
SN - 0022-3263
IS - 24
ER -