Abstract
Hydrolysis/[3 + 2] cycloaddition/elimination cascades employed for the synthesis of unexpected tricyclic compound derived from isoquinoline. Reaction of ethylene derivative 1 with the isoquinoline ester iminium ion 2 in alkaline medium (MeOH/NEt3) under reflux for 1 h resulted in the formation of the fused pyrrolo[2,1-a]isoquinoline derivative 3. Its structure was elucidated by X-ray single crystal and other spectrophotometric tools. Hirshfeld calculations for 3 and its crystal structure analysis revealed the importance of the short O horizontal ellipsis H (19.1%) contacts and the relatively long H horizontal ellipsis C (17.1%), Cl horizontal ellipsis H (10.6%) and C horizontal ellipsis C (6.1%) interactions in the molecular packing. DFT calculations were used to compute the electronic and spectroscopic properties of the studied system. The studied compound has polar nature (3.5953 Debye). TD-DFT calculations assigned the shortest wavelength band (220 nm) to the HOMO-1 -> LUMO+2 (57%), HOMO-1 -> LUMO+4 (14%) mixed excitations. The calculated NMR chemical shifts correlated very well with the experimental data (R-2 = 0.93-0.94).