N-Substituted 2-iodobenzamides and enaminones undergo cascade transformations to achieve quinazolinones via a copper-catalyzed Ullmann-type coupling, a Michael addition and a retro-Mannich reaction. A unique stereochemical feature of this domino process was that Z-enaminones reacted without external ligands, whereas E-enaminones required the assistance of ligands.
SnAP (Sn (tin) amine protocol) hydrazine reagents and aldehydes undergo oxidative, copper mediated coupling to form substituted 1,4,5‐oxadiazepanes and 1,2,5‐triazepanes. Unlike all prior reactions involving SnAP reagents, the SnAP hydrazine reagents undergo a molecular oxygen‐assisted oxidative cyclization. The air‐ and moisture tolerant transformation accommodates a broad range of groups including electron‐rich, electron‐poor aromatic, heteroaromatic, and aliphatic aldehydes and is amenable to gram scale synthesis. These unusual, chiral heterocycles have unexpectedly large optical rotations, which may find use in optical materials.
A convenient and practical thiocyanation of pyrazoles is reported employing a combination of KSCN and K 2 S 2 O 8 in dimethyl sulfoxide (DMSO). The salient features of the present reaction include environmentally benign reagents and solvents, and simple operation. The reaction shows wide functional group tolerance and gives moderate to excellent yields.
All isolated compounds were characterized on the basis of 1 H NMR and 13 C NMR spectroscopic data, IR spectra, and HRMS data. 1 H NMR and 13 C NMR spectra were recorded on a Bruker Ascend™ spectrometer. 1 H NMR and 13 C NMR chemical shifts are reported in ppm using tetramethylsilane (TMS) as an internal standard or residual nondeuterated solvent peak as an internal standard. Infrared spectra were recorded with a Bruker ALPHA FT-IR spectrometer. High-resolution mass spectra (HRMS) were recorded with a Bruker micro TOF spectrometer in the ESI mode. Melting points were recorded with a Sanyo Gallenkamp apparatus. Reactions were monitored by thin-layer chromatography and visualized by UV and a solution of KMnO4. Purification of the reaction products was carried out by column chromatography on silica gel (0.063-0.200 mm). After column chromatography, analytically pure solid was obtained by crystallization from CH2Cl2-hexanes. General procedure for the synthesis of 1,3-diketones 1b-1k and 5b-5d 1,2 To a mixture of the ester (15 mmol) and NaH (30 mmol) in toluene (4 mL) was added acetone (or acetophenone derivative (15 mmol) in case of 5b-5d) dropwise at 40 °C within a period of 6 h with stirring. The mixture was stirred at refluxing temperature for one more hour until all the H2 was evolved or monitored by TLC. After cooling down to room
Syntheses of Quinazolinones from 2-Iodobenzamides and Enaminones viaCopper-Catalyzed Domino Reactions. -The double bond geometry of the enaminones plays a crucial role since E-enaminones show a significantly enhanced reactivity upon addition of an external ligand whereas Z-enaminones do not require the latter. The steric hindrance of the enaminone and the nucleophilicity of the amide nitrogen strongly influences the reaction yields. -(SONGSICHAN, T.; PROMSUK, J.; RUKACHAISIRIKUL, V.; KAEOBAMRUNG*, J.; Org. Biomol. Chem. 12 (2014) 26, 4571-4575, http://dx.doi.org/10.1039/c4ob00400k ; Dep. Chem., Prince Songkla Univ., Hat Yai 90112, Thailand; Eng.) -F. Schill 49-172
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