A facile microwave assisted synthesis and structure elucidation of (3R)-3-alkyl-4,1-benzoxazepine-2,5-diones by crystallographic, spectroscopic and DFT studies

Author(s)

Raza, Abdul Rauf ^[1] ; Nisar, Bushra ^[2] ; Khalid, Muhammad ^[3] ; Gondal, Humaira Yasmeen ^[1] ; Khan, Muhammad Usman ^[4] ; de Alcantara Morais, Sara Figueiredo ^[5] ; Tahir, Muhammad Nawaz ^[6] ; Braga, Ataualpa Albert Carmo ^[5]

Affiliation

^[1] Univ Sargodha, Dept Chem, Ibn E Sina Block, Sargodha 40100 - Pakistan

^[2] Univ Lahore, Dept Chem, Sargodha Campus, Sargodha 40100 - Pakistan

^[3] Khwaja Fareed Univ Engn & Informat Technol, Dept Chem, Rahim Yar Khan 64200 - Pakistan

^[4] Univ Okara, Dept Chem, Okara 56300 - Pakistan

^[5] Univ Sao Paulo, Inst Quim, Dept Quim Fundamental, Ave Prof Lineu Prestes 748, BR-05508000 Sao Paulo - Brazil

^[6] Univ Sargodha, Dept Phys, Ibn ul Hathim Block, Sargodha 40100 - Pakistan

• Document type: Journal article
• Source: SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY; v. 230, APR 5 2020.
• Web of Science Citations: 5

Abstract

The use of microwave (MW) irradiation in organic synthesis has become increasingly popular within the pharmaceutical and academic arenas because it is a new enabling technology for drug discovery and development. It is a rapid way of synthesis center dot which involves faster reaction rates and high selectivity to conventional heating method of syntheses. The MW-assisted 7-exo-tet cyclization of N-acylanthranilic acids afforded (3R)-3-alkyl-4,1-benzoxazepines-2,5-diones in very short duration (20 min) with extraordinary high yields in comparison to conventional heating mode of synthesis. The method development, comparative yields of MW-assisted and thermal method of syntheses, crystallographic, spectroscopic and density functional theory (DFT) studies are reported herein. Four novel compounds with chemical formulas C(10)H(19)BrClNO(3)5m, C19H19NO3 6e, C13H14ClNO3 6h and C12H11Br2NO3 6h were synthesized, validated by (HNMR)-H-1, (CNMR)-C-13, FT-IR, UVVis, EIMS spectroscopic techniques and confirmed by using single crystal X-ray diffraction (SC-XRD) study. The DFT and TDDFT calculations at B3LYP/6-31 1 G(d,p) level of theory were performed for comparative analysis of spectroscopic data, optimized geometries, frontier molecular orbitals (FMOs), natural bond orbital (NBO) analysis and nonlinear optical (NLO) properties of Sm, 6e, 6h and 6o. Overall, experimental findings were supported nicely by corresponding NT computed results. The NBO analysis confirmed that the presence of non-covalent interactions, hydrogen bonding and hyper- conjugative interactions are pivotal cause for the existence of 5m, 6e, 6h and 6o in the solid-state. NLO analysis showed that 5m, 6e, 6h and 6o have significant NLO properties as compared to prototype standard compound which disclosed their potential for technology related applications. (C) 2020 Elsevier B.V. All rights reserved. (AU)

• FAPESP's process: 15/01491-3 - Theoretical study of cross-coupling reactions: homogeneous and heterogeneous catalysis
• Grantee: Ataualpa Albert Carmo Braga
• Support type: Regular Research Grants
• FAPESP's process: 14/25770-6 - New frontiers in cross-coupling reactions promoted by palladium: combining enantioselective catalysis, C-H activations, new materials and in flux reactions aiming at high efficiency and sustainability in synthetic processes
• Grantee: Carlos Roque Duarte Correia
• Support type: Research Projects - Thematic Grants
• FAPESP's process: 11/07895-8 - Theoretical study of the Heck-Matsuda reactions
• Grantee: Ataualpa Albert Carmo Braga
• Support type: Scholarships in Brazil - Post-Doctorate