ChemInform Abstract: Reactivity and Selectivity of Captodative Olefins as Dienes in Hetero‐Diels—Alder Reactions.

Abstract

The reactivity and selectivity of the the captodative olefins 1-acylvinyl benzoates 1a -1f and 3a as heterodienes in hetero-Diels -Alder reactions in the presence of electron-rich dienophiles is described. Heterodienes 1 undergo regioselective cycloaddition with the alkyl vinyl etherdienophiles 6a,b and 9 to give the corresponding dihydro-2H-pyrans 7, 8, and 10 under thermal conditions. The reactivity of these cycloadditions depends, to a large extent, on the electronic demand of the substituent in the aroyloxy group of the heterodiene. Frontier-molecular-orbital (FMO; ab initio) and density-functional-theory (DFT) calculations of the ground and transition states account for the reactivity and regioselectivity observed in these processes.

Thermochemical Study of 1-Acetyl Vinyl p-Nitrobenzoate: Vinyl Bond Enthalpy in Captodative Olefins

“…Because of the interest in the reactivity behavior of these molecules as dienophiles, dipolarophiles, and dienes in cycloaddition reactions as well as on their versatile application in the synthesis of naturally occurring products, − we prompted ourselves to investigate their thermodynamic properties. Thermochemical values such as the gas-phase formation enthalpy are valuable, for example, for directly quantifying the energy associated with the olefinic bond where the Diels–Alder addition takes place.…”