HDA cycloadditions of 1-diethoxyphosphonyl-1,3-butadiene with nitroso heterodienophiles: A computational investigation

Abstract

a b s t r a c tThe hetero Diels-Alder (HDA) reactions of 1-diethoxyphosphonyl-1,3-butadiene with various nitroso dienophiles have been studied at the B3LYP/6-31G** level. Structural, energetic and electronic properties are discussed. These cycloadditions with nitroso dienophiles are characterized by a total proximal regioselectivity and an endo selectivity. The influence of the nitroso substitution on the activation barrier and the regiochemistry of the reaction is presented. The analysis of the chemical rearrangement along the intrinsic reaction pathway (IRC), based on bond order and on natural bond orbital (NBO) calculations, emphasizes the polar nature of these cycloadditions. Despite the early and the cyclic nature of the corresponding transition states, a two-center interaction governs this mechanism: these cycloadditions are Polar Diels-Alder reactions (P-DA).

Stereo- and regioselectivity of the hetero-Diels–Alder reaction of nitroso derivatives with conjugated dienes

“…Thus, the regioselectivity of this reaction was studied by several groups, e.g., [79–80 84,86,88–90], and it was confirmed to be highly dependent on several factors. These are for example the number and nature of substituents on the diene and the dienophile, and the reaction conditions such as temperature, pressure, solvent, and presence of catalyst, etc.…”

“…In 2010, the Marchand–Brynaert group published several results of asymmetric hetero-Diels–Alder reactions of phosphonyl-1,3-butadienes with various nitroso dienophiles [21,85–87]. A computational investigation of the hetero-Diels–Alder reactions of 1-diethoxyphosphonyl-1,3-butadiene ( 28 ) with various nitroso heterodienophiles 29 (Scheme 8) was determined at the B3LYP/6-31G** level [86]. All calculations were performed with density functional theory (DFT) using the B3LYP functional implemented in the Gaussian 98 software.…”