Open AccessCan Aromaticity of Fused Aromatic Ring in 1,3-Pentadiene Modulate its Reactivity towards [1,5]-Halo Shift? - A DFT Study
Author(s) -
P Kalpana,
Lakshminarayanan Akilandeswari
Publication year - 2021
Publication title -
asian journal of chemistry/asian journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.145
H-Index - 34
eISSN - 0975-427X
pISSN - 0970-7077
DOI - 10.14233/ajchem.2021.23092
Subject(s) - aromaticity , chemistry , pericyclic reaction , ring (chemistry) , benzene , computational chemistry , fluorine , halogen , transition state , naphthalene , chemical shift , organic chemistry , molecule , alkyl , catalysis
In (Z)-1,3-pentadienes, [1,5]-H migration is suprafacially allowed while fluorine shift in this systemtakes place by a Contra Hoffmann antarafacial pathway for which aromaticity is the driving force. Ifaromaticity of the transition structure (TS) can drive a reaction towards a disallowed pathway as foundin the case of fluorine, the role of aromatic ring annealed to (Z)-1,3-pentadienes in determining thereaction pathway and barrier is worth noting. Hence, the combined role of aromaticity of transitionstate and the loss in aromaticity of the annealed ring has been explored during the [1,5]-X (X = H, F,Cl, Br) shifts in aromatic (benzene/naphthalene) annealed 1,3-pentadiene system. Notable correlationsbetween various aromaticity index NICS(0,1) with activation barriers show that aromaticity of transitionstructure in pericyclic reaction can drive the stereochemical course of a reaction. The distinct effect offluorine to other halogens is the antara migration while the other halogens (Cl & Br) prefer supramode.