Several Methodologies For Functional Thoethers And Sulfones

Sulfur-containing functional groups pervasively exist in pharmaceuticals,flavors,organic photoelectric materials and bioactive natural products,which are important constitutional units in functional organic molecules.Thioethers and sulfones are two significant sulfur containing organic compounds.Several innovative and highly efficient methodologies for their construction were developed and corresponding sulfur-containing functional compounds can be afforded in moderate to high yield.This thesis includes two parts:Part Ⅰ:The construction of low-valence thioesters.1)Pd-catalysted Csp²-H sulfenylation of sulfur containing substrates was described,in which electron-withdrawing protecting group act as a mask.The introduction of the mask prevents poisoning of catalyst and oxidation to disulfides.Many sulfur-containing benzoheterocyclics,BTBT and BTT were efficiently synthesized.Mechanistic studies indicated that the disulfides were not the key intermediates of the reaction.Part Ⅱ:Construction of high-valence sulfones1)The SO_2/I exchange protocol aimed at the organic materials was established,which accomplished the construction of the diarylannulated sulfones using inorganic sulfides.This method using diaryliodonium salts as the substrates,Na₂S₂O₅ as a sulfur dioxide source,constructed diverse functionalized diarylannulated sulfones,which are essential units in organic materials.Six-membered diarylannulated sulfones were also obtained in moderate to good yields under the metal-free conditions.Mechanism studies proved that a free radical process is present in the reaction system.2)The sulfones are indispensable in pharmaceuticals.An efficient methodology for their construction via reductive coupling has been described.A lot of sulfones could be prepared through one-pot method from alkyl/aryl halide,NaS₂O₄ or thiourea dioxide and phosphate ester,in which the sulfur dioxide surrogate plays a role of reductant.The low catalyst loading and the compatibility of substrates reveal its versatility and applicability.