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The Origin of endo Stereoselectivity in the Hetero‐Diels–Alder Reactions of Aldehydes with ortho ‐Xylylenes: CH–π, π–π, and Steric Effects on Stereoselectivity
Author(s) -
Ujaque Gregori,
Lee Patrick S.,
Houk K. N.,
Hentemann Martin F.,
Danishefsky Samuel J.
Publication year - 2002
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/1521-3765(20020802)8:15<3423::aid-chem3423>3.0.co;2-x
Subject(s) - stereoselectivity , benzaldehyde , steric effects , chemistry , aldehyde , ring (chemistry) , selectivity , alkyl , transition state , organic chemistry , medicinal chemistry , computational chemistry , catalysis
Theoretical studies of stereoselectivity have been carried out with B3LYP and MP2 calculations. The high endo selectivity of hetero‐Diels–Alder reactions of ortho ‐xylylenes with acetaldehydes is shown to result from attractive CH–π interactions between alkyl groups of the aldehyde and the aromatic ring in the transition states of the reaction. For the hetero‐Diels–Alder reactions of ortho ‐xylylenes with benzaldehyde, the stereoselectivity is shown to be mainly governed by the attractive π–π interactions between the phenyl rings of the benzaldehyde and the ortho ‐xylylene. MP2 calculations are necessary to reproduce the stabilizing dispersion interactions.