Halocyclization of Olefinic 1,3-Dicarbonyls and Olefinic Amides in Aqueous Media Open in Air at Room Temperature

Abstract

A green and efficient procedure for the preparation of valuable 2,3-dihydrofurans and benzoxazines has been achieved through halocyclization of olefinic 1,3-dicarbonyls or olefinic amides. This protocol could be conducted under catalyst-, base-, and oxidant-free conditions in aqueous media open to the air at room temperature with good to excellent yields. Notably, the practicality of this method is further highlighted by gram-scale reactions in good yields.

Metal-Catalyst-Free Radical Cyclization of 1,6-Enynes for the Selective and Switchable Synthesis of Lactams in Water

“…The commonly used organic solvents are generally volatile and toxic, so it is a sustainable choice to find environmentally friendly media as an alternative. − As the greenest and safest solvent in nature, water has drawn the attention of chemists due to its excellent biocompatibility, nonflammability, and nontoxicity. − Hence, it is of great significance to exploit organic reactions in aqueous media. In addition, the development of the metal-catalyst-free method is also booming due to its low toxicity, long service life, and simple postprocessing. − Inspired by these advances and as a continuation of our efforts in radical cyclization of unsaturated hydrocarbons, − we present a sustainable and switchable radical cyclization of 1, n -enynes with sulfonyl hydrazines in aqueous media without a metal catalyst to form five-membered cyclic lactams, five-membered cyclic lactams containing C–I bond, and six-membered cyclic lactams (Scheme -2). These protocols have the following prominent advantages: (1) water as the solvent; (2) metal-catalyst-free; (3) high selectivity and controllability; and (4) preparation of diversified products from the same substrate.…”

Iron-Mediated Bromocyclization of Olefinic Amides for the Synthesis of Bromobenzoxazines

“…1 H NMR (400 MHz, CDCl 3 ): δ 8. 2H,NH and ArH),2H,ArH),3H,ArH),1H,ArH),7.19 (dd, J 1 = 2.0 Hz, J 2 = 8.0 Hz, 1H, ArH), 7.12 (m, 1H, ArH), 5.48 (t, J = 1.6 Hz, 1H, CH 2 ), 5.12 (d, J = 0.8 Hz, 1H, CH 2 ), 2.12 (s, 3H, CH 3 ). 13 C NMR (101 MHz, CDCl 3 ): δ 165.…”

Green Tandem [5C + 1C] Cycloaromatization of α-Alkenoyl Ketene Dithioacetals and Nitroethane in Water: Eco-Friendly Synthesis of Ortho-Acylphenols

“…Owing to the safe, non-toxic, and abundant properties of water, organic synthesis in water, which significantly reduces toxic wastes, is one of the important research fields in green and sustainable chemistry. , Tandem reactions, as a very powerful methodology for the efficient construction of complex products from simple starting materials in one pot, continue to receive increased attention due to their excellent synthetic efficiency and atom economy, as well as the minimal production of waste. , Ortho -acylphenols were not only a class of important organic compounds with good bioactivities (Figure ) but also prime intermediates for the synthesis of various potentially bioactive molecules . Over the past decades, considerable methods for the synthesis of ortho -acylphenols had been developed, including Friedel–Crafts acylation reactions of phenols, Fries rearrangement of phenyl ester, direct C–H bond arylation of 2-hydroxy benzaldehydes, transition metal catalyzed C–H bond carbonylation of phenols and their derivatives, C–H bond oxylation of diarylmethanone, Cu-catalyzed oxidative deamination of Betti bases, cyclization of acyclic substrates, and other methods .…”