| In recent years,with strengthening environmental awareness in the whole society,the concept of green synthetic chemistry became popular topics in chemistry research.Solvent-free synthesis,water phase synthesis,and catalyst-free or metal-free catalytic synthesis have become a pursuing target of synthetic chemists.The nitrogen,sulfur and phosphorus containing compounds,such as isoindolinones,benzothiazoles,and thiophosphates,are important functional molecules,and their units are widely found in natural compounds and drug molecules.In this context,our objectives are to develop new green protocols to construct C-N,C-C,C-S and S-P bonds for the synthesis of a variety of nitrogen,sulfur,phosphorus-containing,organic functional molecules.The main work includes the following five parts:In chapter 2,a facile and enviromentally benign approach toward the synthesis of novel 3-alkyl substituted isoindolinones by three-component reactions of 2-formylbenzoic acids,primary amines and 2-methylazaarenes in water under catalyst-free conditions is herein described.This protocol features the direct construction of multiple C-N and C-C bonds via a tandem Mannich-type reaction and intramolecular cyclization in a one-pot fashion.A broad scope of primary amines and azaarenes can be tolerated,and a series of 3-(2-quinolinemethylene)-substituted isoindolinones were prepared in good to excellent yields.Phthalaldehydic acid also as Br(?)nsted acid played a key role in the functionalization of methyl group from 2-methylquinoline.Importantly,this reaction could be readily gram-scaled without obviously decreased yield,and it is very meaningful for future application.In chapter 3,An efficient and environmentally friendly protocol for the synthesis of isoindolinones by a three-component reactions of 2-formylbenzoic acids,primary amines,2-naphthols via a Mannich-cyclization reaction sequence in water under catalyst-free conditions is described here.This approach distinguishes the following advantages,such as the use of the environmentally benign while naturally abundant water as the reaction medium.What's more,the extrusion of water as the only byproduct,the column chromatography-free work-up procedure and purified by only simple recrystallization from EtOH and H2O,easily scaled-up practice,together with the metal-free conditions,all these tailor-made merits make the current developed methodology potentially useful in industrial application.In chapter 4,we have developed an efficient catalyst-free reductive amination/cyclization cascade of 2-formylbenzoic acids with amines for the construction of biologically important isoindolinone derivatives.This is the first example of catalyst-free biomimetic synthesis of N-substituted isoindolinones.This approach operates with a cheap and readily accessible Hantzsch ester as the reductant,wide substrate scope,ease of operation,representing the first straightforward thus viable synthetic route toward the synthesis of medicinally relevant isoindolinones.And N-substituted isoindolinone was purified by recrystallization.In chapter 5,we have developed a one-pot synthesis of 2-substituted benzothiazoles via redox condensation of o-chloronitroarenes and benzyl halides with elemental sulfur using N-methylmorpholine and piperidine as base under solvent-free condition.It was found that elemental sulfur plays dual roles as reactant and redox agent for this transformation.Noteworthy features of the protocol are mild reaction conditions,inexpensive starting materials,operation simplicity and good yield.In chapter 6,an efficient I2O5 and DBU-catalyzed oxidative S-P(O)coupling method has been developed for the synthesis of biologically active thiophosphates.The reaction proceeds well at room temperature with various aromatic thiols and H-phosphonates,affording a series of thiophosphates in moderate to good yields.Compared with other methods,this protocol is featured with mild conditions without other metal catalysts or organic peroxide. |
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