Efficient Synthesis of Maleimides and Carbazoles via Zn(OTf)₂-Catalyzed Tandem Annulations of Isonitriles and Allenic Esters

Abstract

Lewis acid Zn(OTf)(2)-catalyzed tandem annulations of isonitriles and allenic esters which lead to efficient and flexible syntheses of a range of biologically significant maleimides and carbazoles and related compounds are reported. A mechanistic rationale is proposed to account for the observed reactivity.

Silver salts and DBU cooperatively catalyzed domino reaction of propargylic alcohols with trifluoromethyl ketones: direct method to trifluoromethyl‐substituted 5‐alkylidene‐1,3‐dioxolane derivatives

“…Silica gel (200–300 mesh) was used for flash chromatography. Trifluoromethyl ketones and propargylic alcohols were prepared according to the literature.…”

Applications of C–H Functionalization Logic to Cyclobutane Synthesis

“…This compound was prepared analogously to 31 , only employing N -tosyl-3-iodoindole 56 (263 mg), and purified by silica gel chromatography (1/1/3 to 3/3/4 DCM/Et 2 O/hexanes) to give 33 (156.1 mg, 92%) as light yellow crystals. Crystals suitable for X-ray diffraction were obtained from EtOAc: pale yellow crystals (185–187 °C); R f = 0.1 (silica gel, 3/1 hexanes/EtOAc); HRMS ( m / z ) calcd for C 44 H 36 N 4 O 5 S 2 ([M + H] + ) 765.2205, found 765.2198; IR (film) ν max br 3346, 2940, 1680, 1520, 1362, 1170, 1124, 736 cm –1 ; 1 H NMR (400 MHz, CDCl 3 ) δ 9.57 (s, 1 H), 8.70 (dd, J = 4.3, 1.7 Hz, 1 H), 8.47 (dd, J = 7.1, 2.0 Hz, 1 H), 8.05 (dd, J = 8.3, 1.7 Hz, 1 H), 7.84–7.77 (m, 2 H), 7.73 (s, 2 H), 7.58–7.54 (m, 2 H), 7.52 (d, J = 8.4 Hz, 4 H), 7.44–7.33 (m, 3 H), 7.22–7.11 (m, 4 H), 6.82 (d, J = 8.0 Hz, 4 H), 4.28–4.10 (m, 3 H), 3.61–3.48 (m, 1 H), 2.99–2.87 (m, 1 H), 2.13 (s, 6 H); 13 C NMR (CDCl 3 , 101 MHz) δ 168.7, 148.2, 144.2, 138.1, 136.0, 135.2, 134.9, 134.2, 130.6, 129.6, 127.7, 127.1, 126.6, 125.0, 124.4, 123.0, 121.6, 121.4, 121.1, 119.3, 116.2, 113.6, 53.8, 33.1, 31.9, 21.4.…”

Synthesis, Antibacterial, and Antifungal Activities of Novel Pyridazino Carbazoles

“…Reaction works even faster and smoother to reveal the product 9 in 73% yield. Spectral data, that is, elemental analysis, IR, 1 H NMR, 13 CNMR, MS, was supporting successful formation of 2. Absorption observed in IR spectrum was at 3418 (NH), 3040 (aromatic), and 1604 cm 1 (C=O bond).…”

“…Synthesis and Characterization. Carbazole and its derivatives are privileged natural product motifs that are dowered with enormous properties and exclusive biological pro�le [12,13]. e current work emphasizes the synthesis of novel carbazoles to fuel up the class of these versatile compounds with some novel derivatives.…”