TY - JOUR
T1 - Controlling cis/trans-selectivity in intramolecular Diels-Alder reactions of benzo-tethered, ester linked 1,3,9-decatrienes
AU - Pearson, Emma L.
AU - Willis, Anthony C.
AU - Sherburn, Michael S.
AU - Paddon-Row, Michael N.
PY - 2008
Y1 - 2008
N2 - Predictions from DFT (B3LYP/6-31 G(d))-computed stereoisomer product distributions for intramolecular Diels-Alder (IMDA) reactions have been successfully replicated in the laboratory. Benzo-tethered hexadienyl acrylates generally undergo moderately trans-selective IMDA reactions which, as suggested by DFT calculation, arise from two opposing transition structure (TS) features: stabilising secondary orbital interactions, which are stronger in the cis-TSs, and stabilising π-conjugative interactions between the benzo moiety and the 1,3-diene component - which are stronger in trans-TSs. Substrates carrying a removable substituent (i.e. Br or TMS) at C3 of the diene or C12 of the aromatic ring are predicted to undergo highly cis-selective thermal IMDA reactions by steric destabilisation of the trans-TS. A substrate carrying a two atom tether between C3 and C12 is predicted to undergo a highly trans-selective intramolecular cycloaddition by destabilisation of the cis-TS. These calculations are borne out experimentally.
AB - Predictions from DFT (B3LYP/6-31 G(d))-computed stereoisomer product distributions for intramolecular Diels-Alder (IMDA) reactions have been successfully replicated in the laboratory. Benzo-tethered hexadienyl acrylates generally undergo moderately trans-selective IMDA reactions which, as suggested by DFT calculation, arise from two opposing transition structure (TS) features: stabilising secondary orbital interactions, which are stronger in the cis-TSs, and stabilising π-conjugative interactions between the benzo moiety and the 1,3-diene component - which are stronger in trans-TSs. Substrates carrying a removable substituent (i.e. Br or TMS) at C3 of the diene or C12 of the aromatic ring are predicted to undergo highly cis-selective thermal IMDA reactions by steric destabilisation of the trans-TS. A substrate carrying a two atom tether between C3 and C12 is predicted to undergo a highly trans-selective intramolecular cycloaddition by destabilisation of the cis-TS. These calculations are borne out experimentally.
UR - http://www.scopus.com/inward/record.url?scp=38849204411&partnerID=8YFLogxK
U2 - 10.1039/b716910h
DO - 10.1039/b716910h
M3 - Article
SN - 1477-0520
VL - 6
SP - 513
EP - 522
JO - Organic and Biomolecular Chemistry
JF - Organic and Biomolecular Chemistry
IS - 3
ER -