Hashemi M, Taherpour AA. Structural Assessment of Hydrogen Bonds on Methylpentynol-Azide Clusters To Achieve Regiochemical Outcome of 1,3-Dipolar Cycloaddition Reactions Using Density Functional Theory.
ACS OMEGA 2020;
5:5964-5975. [PMID:
32226877 PMCID:
PMC7098023 DOI:
10.1021/acsomega.9b04333]
[Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 02/27/2020] [Indexed: 06/10/2023]
Abstract
This study was focused on the geometries and properties of the structural isomers obtained from a random walk of methylpentynol-HN3 clusters. The theoretical aspects of hydrogen bonding effects on the discussed 1,3-dipolar cycloaddition (1,3-DC) reactions [between methylpentynol (a) as a dipolarophile and azide (b) as a 1,3-dipole] have shown regioselective output concepts. The dipolarophile methylpentynol (a) was applied for the treatment of insomnia. Both methylpentynol (a) and azide (b) can be H-bond acceptor and H-bond donor agents. Because of this trait of them, structures of H-bonding arrays (c-f) and methylpentynol-azide clusters (g-m) can be probable. In this work, regioselectivity of the 1,3-DC reaction [between methylpentynol (a) as a dipolarophile and azide (b) as a 1,3-dipole] was determined based on these structures (c-m) using density functional theory (DFT). The energy levels of the reactants (a and b) and the structures of H-bonding arrays (c-f), methylpentynol-azide clusters (g-m), transition states, and products (1 and 2) were studied, and also, the free energies of the reaction (Δr G and ΔG #, in kcal mol-1) and rate constants were determined using Eyring's equation (k). Structural data were calculated and obtained by the DFT/B3LYP method. Seven different basis sets have been used to obtain the most appropriate results from comparison of data.
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