Synthesis Methodologies Of Unsymmetrical Disulfide And 3-Sulfenylindoles

Sulfur-containing organics play important roles in medicine,biology and chemistry due to their anti-inflammatory and anti-cancer characteristics.The synthesis of organic sulfides has always been attracting significant attention in organic chemistry.Here,four green methods without the use of transition metals were developed for the synthesis of unsymmetrical disulfides and 3-sulfenylindoles under the guidance of the established“simple and efficient synthesis”concept.A series of organosulfur compounds were synthesized in excellent yields and the challenge of the“pungent smell”often encountered in organosulfur chemistry was partially addressed.The main contents of the dissertation are as follows:1.The history,status quo and latest advances regarding the synthesis of unsymmetrical disulfides and 3-sulfenylindoles were systematically reviewed.2.An aqueous three-component reaction between thioacetates,Na₂S₂O₃,and benzyl chlorides was successfully performed using Cs₂CO₃（15–30 mol%）as catalyst to synthesize various unsymmetrical disulfides without the presence of any other additives.This synthesis is a one-step/one-pot S_N2 reaction between Bunte salts and thioacetates.The use of Na₂S₂O₃ not only avoids the“pungent smell”in traditional organosulfur chemistry,but also accomplishes the transformation of“inorganic sulfur”into“organic sulfur”.3.The“one-pot”reaction between thiosulfonates,thiourea,and benzyl bromides was successfully performed under mild conditions using 1.0 equivalent of K₂CO₃ as additive to efficiently synthesize simple unsymmetrical disulfides without the presence of catalysts such as transition metals.This approach was also applied to the introduction of the disulfide bond into some natural products like amino acids and oestrone.The S_N2reaction between thiosulfonates and isothiuronium salts is directly accountable for the formation of disulfide bond.4.The cross-coupling reaction between indoles and Harpp reagents at room temperature catalyzed by Li Br（20 mol%）using DMAc as solvent was successfully performed,affording novel unsymmetrical disulfides bearing indole-skeleton.This synthesis approach,to a certain extent,counteracts the defect of“structural monotony”in disulfide synthesis,and the reaction was mechanistically confirmed to be a Friedel-Crafts-type reaction.5.A Friedel-Crafts-type C3-sulfenylation between thiosulfonates and indoles at room temperature catalyzed by Rose Bengal（5 mol%）using 4.0 equivalent of Mg Cl₂as additive was successfully performed.Various 3-sulfenylindoles were prepared in up to 90%isolated yield by this simple method.In addition,the use of thiosulfonates in 3-sulfenylindoles synthesis partially counteracts the defect of“scarce S source”.