TY - JOUR
T1 - Light-induced geometric isomerization of 1,2-diphenylcyclopropanes included within Y zeolites
T2 - Role of Cation-guest binding
AU - Kaanumalle, Lakshmi S.
AU - Sivaguru, J.
AU - Sunoj, R. B.
AU - Lakshminarasimhan, P. H.
AU - Chandrasekhar, J.
AU - Ramamurthy, V.
PY - 2002/12/13
Y1 - 2002/12/13
N2 - Through a systematic study of several diphenylcyclopropane derivatives, we have inferred that the cations present within a zeolite control the excited-state chemistry of these systems. In the parent 1,2-diphenylcylopropane, the cation binds to the two phenyl rings in a sandwich-type arrangement, and such a mode of binding prevents cis-to-trans isomerization. Once an ester or amide group is introduced into the system (derivatives of 2β,3β-diphenylcyclopropane-1α-carboxylic acid), the cation binds to the carbonyl group present in these chromophores and such a binding has no influence on the cis-trans isomerization process. Cation-reactant structures computed at density functional theory level have been very valuable in rationalizing the observed photochemical behavior of diphenylcyclopropane derivatives included in zeolites. While the parent system, 1,2-diphenylcylopropane, has been extensively investigated in the context of chiral induction in solution, owing to its failure to isomerize from cis to trans, the same could not be investigated in zeolites. However, esters of 2β,3β-diphenylcyclopropane-1α-carboxylic acid could be studied within zeolites in the context of chiral induction. Chiral induction as high 20% ee and 55% de has been obtained with selected systems. These numbers, although low, are much higher than what has been obtained in solution with the same system or with the parent system by other investigators (maximum ∼10% ee).
AB - Through a systematic study of several diphenylcyclopropane derivatives, we have inferred that the cations present within a zeolite control the excited-state chemistry of these systems. In the parent 1,2-diphenylcylopropane, the cation binds to the two phenyl rings in a sandwich-type arrangement, and such a mode of binding prevents cis-to-trans isomerization. Once an ester or amide group is introduced into the system (derivatives of 2β,3β-diphenylcyclopropane-1α-carboxylic acid), the cation binds to the carbonyl group present in these chromophores and such a binding has no influence on the cis-trans isomerization process. Cation-reactant structures computed at density functional theory level have been very valuable in rationalizing the observed photochemical behavior of diphenylcyclopropane derivatives included in zeolites. While the parent system, 1,2-diphenylcylopropane, has been extensively investigated in the context of chiral induction in solution, owing to its failure to isomerize from cis to trans, the same could not be investigated in zeolites. However, esters of 2β,3β-diphenylcyclopropane-1α-carboxylic acid could be studied within zeolites in the context of chiral induction. Chiral induction as high 20% ee and 55% de has been obtained with selected systems. These numbers, although low, are much higher than what has been obtained in solution with the same system or with the parent system by other investigators (maximum ∼10% ee).
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U2 - 10.1021/jo026137k
DO - 10.1021/jo026137k
M3 - Article
C2 - 12467381
AN - SCOPUS:0037073877
VL - 67
SP - 8711
EP - 8720
JO - Journal of Organic Chemistry
JF - Journal of Organic Chemistry
SN - 0022-3263
IS - 25
ER -