A Simple, Efficient, and Eco-Friendly Method for the Preparation of 3-Substituted-2,3-dihydroquinazolin-4(1H)-one Derivatives

Abstract

A simple, cost-effective method under environmentally benign conditions is a very important concept for the preparation of 2,3-dihydroquinazolin-4(1H)-one derivatives. The present work describes an efficient and eco-friendly protocol for the synthesis of 2-amino-N-(2-substituted-ethyl)benzamide and 3-substituted-2,3-dihydroquinazolin-4(1H)-one derivatives. The novel feature of this protocol is the use of 2-methyl tetrahydrofuran (2-MeTHF) as an eco-friendly alternative solvent to tetrahydrofuran (THF) in the first step. In the second step, methanol in the presence of potassium carbonate as a catalyst was used under conventional heating or microwave irradiation, which provided an eco-friendly method to afford the target products in excellent yields and purities. NMR (1H and 13C), elemental analysis, and LC-MS confirmed the structures of all compounds. X-ray crystallography further confirmed the structure of the intermediate 2-amino-N-(2-substituted-ethyl)benzamide 3a. The molecular structure of 3a was monoclinic crystal, with P21/c, a = 13.6879 (11) Å, b = 10.2118 (9) Å, c = 9.7884 (9) Å, β = 105.068 (7)°, V = 1321.2 (2) Å3, and Z = 4.

Shaping of the Present-Day Deep Biosphere at Chicxulub by the Impact Catastrophe That Ended the Cretaceous

“…Acoustic borehole images were acquired at the drill Site M0077 with a QL40-ABI probe ( Morgan et al, 2016 ). The tool produces millimeter-scale, high-resolution acoustic images of the borehole wall at 360° ( Zemanek and Caldwell, 1969 ; Lofi et al, 2012 ). Detected fractures are not necessarily connected to deeper or shallower locations since they may be closed or filled away from the borehole wall.…”