Intramolecular Diels–Alder Reactions of Cycloalkenones: Stereoselectivity, Lewis Acid Acceleration, and Halogen Substituent Effects

Abstract

The intramolecular Diels–Alder reactions of cycloalkenones and terminal dienes occur with high endo stereoselectivity, both thermally and under Lewis-acidic conditions. Through computations, we show that steric repulsion and tether conformation govern the selectivity of the reaction, and incorporation of either BF3 or α-halogenation increases the rate of cycloaddition. With a longer tether, isomerization from a terminal diene to the more stable internal diene results in a more facile cycloaddition.

Quantitative conversion of triglycerides to hydrocarbons over hierarchical ZSM-5 catalyst

“…Lewis acid site were able to activate enone dienophiles by lowering the activation barrier in the Diels-Alder reactions of enones [55]. So the Brønsted and Lewis acidity influenced the formation of aromatics.…”

“…According to the literatures, the Diels-Alder cyclization reactions relied on Lewis acidity of the catalysts to a great extent [52][53][54][55][56][57]. Lewis acid site were able to activate enone dienophiles by lowering the activation barrier in the Diels-Alder reactions of enones [55].…”

Highly Enantioselective Construction of Tricyclic Derivatives by the Desymmetrization of Cyclohexadienones

“…These results are in agreement with those of other [4+2] calculations. [28] For the more stable endo approaches, the pathway endo-TS-1 (see Figure 2), which corresponds to the experimentally observed major enantiomer, evolves to a transition state that is 2.5 kcal mol À1 lower in energy than endo-TS-2. This scenario is consistent with a case of kinetic control of an irreversible reaction, which is generally the source of enantioselectivity phenomena.…”

Understanding the Intramolecular Diels‐Alder Reactions of N‐Substituted N‐Allyl‐Furfurylamines: An MEDT Study

“…The DA reaction can be intermolecular or intramolecular (IMDA) depending on the nature of the diene and dienophile which leads to the formation of six‐membered carbocyclic structures . The IMDA reaction permits the formation of contiguous cycles in only one synthetic step and with remarkable stereoselectivity . This reaction is used as routes in the total synthesis of natural products ,…”