Heteroaryl Compound And α-acyloxy Ketone Synthesis By Tandem Reactions Of Enaminones Via Carbon-heteroatom Bond Construction

Enaminones are a class of important synthetic materials which have been used in the synthesis of organic molecules with enriched structural diversity by undergoing divergent transformation pathways.The contents of this synthesis focus on the new tandem reactions featured with carbon-heteroatom bond contruction toward the synthesis of different organic compounds,and three different research works are included.1)Synthesis of sulfonyl pyrazoles via tandem reactions involving C-S bond formation with enaminone-sulfonyl hydrazine reactions.Under transition metal-free conditions,respectively employing NaHCO₃ and TBHP as promoter and oxidant leads to the establishment of the tandem annulation reactions between enaminones and sulfonyl hydrazines via C-H bond sulfonylation,providing a new method for the synthesis of 1,2-disulfonyl pyrazoles.In addition,further treatment on the resulting product with Pd（OAc）₂,1,10-phenanthroline and Cs₂CO₃ allows the selective deprotection of the N-sulfonyl group to afford 4-sulfonyl pyrazole.2)The tandem reactions of enaminones and elemental sulfur for thiophene synthesis in water medium.By using elemental sulfur and enaminones as starting materials,the synthesis of thiophenes is realized via the promotion of NaOH without using transition metal,and the product structure is confirmed by X-ray single crystal analysis.The work provides new route for the green synthesis of thiophenes.3)The C-O forming reactions via enaminone C=C double bond cleavage forα-acyloxyl ketone synthesis.By utilizing aroyl peroxide as oxygen source,the installation of acyloxyl is achieved via enaminone C=C double cleavage in the presence of Mn（II）reagent,affording a new method for the synthesis ofα-acyloxyl ketones.