Understanding the Mechanism of S_N2′ vs. S_N2 in Cascade Reaction of β‐Naphthol and Nitrostyrene Derived MBH Acetates

Abstract

The reaction of β‐naphthol with nitrostyrene derived primary MBH acetates in presence of Cs2CO3 as base resulted in the formation of 3‐nitro‐4‐phenyl‐3,4‐dihydro‐2H‐naphthopyran as the major isomer via SN2′ process. Due to the bis‐electrophilic nature of MBH acetates, the minor product 3‐nitro‐2‐phenyl‐3,4‐dihydro‐2H‐naphthopyran was also obtained presumably due to SN2 process with γ ‐attack on MBH acetates. The state of the art density functional theory (DFT) calculations were carried out to account for these competitive pathways towards the formation of major and minor products.

Recent advances in the synthetic applications of Morita–Baylis–Hillman and Rauhut–Currier adducts of nitroalkenes

“…In 2020, Anwar and co-workers reported the reaction of β-naphthols 53 and MBH acetates 33 using cesium carbonate as the base in chloroform solvent, and they observed the formation of a mixture of regioisomeric pyrans 56 and 57 (Scheme 18). 28 The two different regioisomers were formed as a result of the difference in the reaction mechanism. The major isomer 56 was formed via an S N 2′ reaction followed by Michael addition, whereas the minor isomer 57 was formed by initial S N 2 substitution and subsequent Michael reaction.…”

Fused Imidazo[2,1‐b][1,2,3]triazolo[4,5‐d][1,3]thiazines: One‐Pot Synthesis, Antibiofilim, Bactericidal Effects, and in silico Studies

“…Finally, the key intermediate 2‐((3‐iodoprop‐2‐yn‐1‐yl)sulfonyl)‐1 H ‐imidazole ( 4 ) (69 %) was obtained from the CuI‐catalyzed reaction between 3 and N‐iodomorpholine in THF at room temperature after 2 h (Scheme 2). [30,33a] …”

Synthesis of tetrahydrochromenes and dihydronaphthofurans via a cascade process of [3 + 3] and [3 + 2] annulation reactions: mechanistic insight for 6-endo-trig and 5-exo-trig cyclisation

“… 20 Previously, our group carried out a [3 + 3] cyclization reaction of β-naphthol with primary MBH acetate to study the scope of S N 2′ vs. S N 2 reaction. 21 With our ongoing interest in using nitro styrene derived MBH adducts 22 explored the reactivity of primary and secondary MBH acetate with β-tetralone 1 as our model reaction. Initially, the reaction carried out using β-tetralone 1 with primary MBH-acetate 2, predominantly gave a tetrahydrochromene 3 via [3 + 3] annulation involving 6- endo trig cyclization through Michael/oxa-Michael cascade process.…”