Understanding the Mechanism of S(N)2 ' vs. S(N)2 in Cascade Reaction of beta-Naphthol and Nitrostyrene Derived MBH Acetates

The reaction of beta-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 S(N)2' 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 S(N)2 process with g-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.