The Dynamic Behavior of 2,4,6‐Cycloheptatriene‐1‐carbaldehyde

Abstract

Valence isomerization and additional ring inversion have been observed in 2,4,6‐cycloheptatriene‐1‐carbaldehyde (RCHO) below −134 °C. No other monosubstituted cycloheptatrienes are known to show this dynamic behavior.

Bicyclic endoperoxides and synthetic applications

“…For example, no norcaradiene valence tautomer could be detected for the unsubstituted cycloheptatriene by variable-temperature 7H NMR, even down to -150 °C.137 However, about 3% norcaradiene was detected for the 7-carboxylic acid138 and about 7.5% for the 7-carbaldehyde. 139 In cases where valence isomerization could not be detected by NMR spectroscopy, the existence of such valence tautomerization has been surmised from Diels-Alder reaction products. For instance, cycloheptatriene gives in most cases norcaradiene-type addition.…”

The Di-π-methane Photorearrangement of 2,3-Disubstituted Benzobarrelenes and Benzonorbornadiene − Substituent Effects in Regioselectivity

“…We assume that the carbonyl group of an aldehyde can adopt the desired conformation much better than the carboxylate group can, due to the increased steric repulsion present between the cyclopropane ring and the bulky ϪOR group. Furthermore, it has been demonstrated experimentally [16,27] and theoretically [28] that the interaction between a cyclopropane ring and an aldehyde group is much stronger than that between the cyclopropane ring and an ester group. At this stage, we assume that the destabilizing effect of cyano and formyl groups on cyclopropane ring formation is more pronounced than that of the ester group.…”

Catalytic, Asymmetric Dearomative Synthesis of Complex Cyclohexanes via a Highly Regio- and Stereoselective Arene Cyclopropanation Using α-Cyanodiazoacetates

“…The electronic identities of the C-7 substituents influence the NCD–CHT equilibrium, with strong π-acceptors favoring the norcaradiene valence tautomer (Scheme a). , Access to the desired NCD tautomer necessarily mandates a C-7 disconnection to a geminally disubstituted carbene/carbenoid bearing the requisite stabilizing groups, which can arise from acceptor/acceptor diazo compounds. α-Cyano-acceptor diazo compounds exhibit high reactivity and selectivity in catalytic cyclopropanation reactions of π-systems by virtue of the enhanced carbenoid electrophilicity conferred by the inherent cylindrical symmetry of the nitrile .…”