Guo-Lan Dou

Regio- and stereoselective synthesis of novel dispiropyrrolidine bisoxindole derivatives via multicomponent reactions.

A convenient and efficient method for the synthesis of novel dispiropyrrolidine bisoxindole derivatives by 1,3-dipolar cycloaddition reaction of azomethine ylides has been developed. The synthesis was achieved by using a one-pot multicomponent procedure. The features of this procedure were characterized by the following: mild reaction conditions, high yields, high regio- and stereoselectivity, one-pot procedure, and operational simplicity.

Highly Efficient Synthesis of Polysubstituted Pyrroles via Four-Component Domino Reaction

A highly efficient, catalyst-free synthesis of polysubstituted pyrroles by means of a novel four-component domino reaction of an arylglyoxal monohydrate, an aniline, a dialkyl but-2-ynedioate, and malononitrile is reported. This transformation proceeded via a 6,6a-dihydrofuro[2,3-b]pyrrole as the key intermediate.

Regioselective synthesis of novel spiropyrrolidines and spirothiapyrrolizidines through multicomponent 1,3-dipolar cycloaddition reaction of azomethine ylides.

A series of novel spiropyrrolidines and spirothiapyrrolizidines were synthesized via a three-component 1,3-dipolar cycloaddition reaction of isatin or acenaphthenequinone, sarcosine or thiaproline and 4-hydroxy-6-methyl-3-((E)-3-phenylacryloyl)-2H-pyran-2-ones in refluxing ethanol. Advantages of this method include the availability of starting materials, mild reaction conditions, high yields, and the complete regioselectivity observed.

Highly Regioselective Synthesis of Polysubstituted Pyrroles through Three-Component Reaction Induced by Low-Valent Titanium Reagent

1,2,3,5-Tetrasubstituted and 1,2,3,4,5-pentasubstituted pyrroles may be synthesized through three-component reaction of 1,3-diketones, aldehydes, and amines induced by low-valent titanium reagent. High regioselectivity was achieved. Compared with the classical synthetic method, this new method has the advantages of short reaction time (15 min), high yields, convenient manipulation, and high regioselectivity.

Efficient and Convenient Synthesis of Pyrrolo[1,2-a]quinazoline Derivatives with the Aid of Tin(II) Chloride

An efficient, convenient, one-pot synthesis of 2,3,3a,4-tetrahydropyrrolo[1,2-a]quinazolin-5(1H)-one and 2,3,3a,4-tetrahydropyrrolo[1,2-a]quinazoline-1,5-dione was accomplished in good yields via the novel reductive cyclization of 2-nitrobenzamides with haloketones or keto acids mediated by SnCl(2).2H(2)O system. A variety of substrates can participate in the process with good yields, making this methodology suitable for library synthesis in drug discovery efforts.

One-Pot Synthesis of Quinazolinone Derivatives from Nitro-Compounds with the Aid of Low-Valent Titanium

The synthesis of a series of quinazolinone derivatives such as 2-thioxoquinazolinones, imidazo[1,2-c]quinazolin-5-amines, and benzimidazo[1,2-c]quinazolin-5-amines, starting from nitro-compounds has been described. This general approach features a easy way for access to the target quinazolinone derivatives. The key cyclization step embraces the formation of a thiourea intermediate, mediated by low-valent titanium, and the other important intermediate was also obtained. A variety of substrates can participate in the process with good yields, making this methodology suitable for library synthesis in drug discovery efforts.

Efficient Synthesis of 2-Arylbenzothiazole Derivatives with the Aid of a Low-Valent Titanium Reagent

A novel and facile synthesis of 2-arylbenzothiazole derivatives was accomplished in good yields via the novel reductive cyclization of bis-(2-benzalaminophenyl)disulfide promoted by the TiCl4/Sm system. The advantages of this new method are the easily accessible starting materials, short reaction time, and moderate to good yields.

Efficient and convenient synthesis of indazol-3(2H)-ones and 2-aminobenzonitriles.

A mild, efficient, one-pot protocol for the synthesis of indazole-3(2H)-ones via cyclization of nitro-aryl substrates through low-valent titanium reagent has been described. The method used Triethylamine (TEA) to control pH. Particularly, 2-aminobenzonitriles were synthesized by one step easily. The mechanistic course of the reaction suggests the involvement of an anion leading to an intramolecular cyclization via N-N bond formation.

Facile, efficient, and diastereoselective synthesis of heterohelicene-like molecules.

A concise and efficient route to new and interesting heterohelicene-like molecules has been developed through the one-pot, cascade reductive coupling reaction of o-hydroxydiimines or o-nitrodiimines and triphosgene in the presence of TiCl4/Sm. Purification of the final products only required a single recrystallization leading to high purity. High diastereoselectivity was also achieved, and two structures of the final products were confirmed by X-ray diffraction analysis.

Efficient Synthesis of Naphtho[1,2-e][1,3]oxazine Derivatives via a Chemoselective Reaction with the Aid of Low-Valent Titanium Reagent

A series of new naphtho[1,2-e][1,3]oxazine derivatives such as trans-1,3-diaryl-1H-naphtho[1,2-e][1,3]oxazine-2(3H)-carbonyl chloride, 1-aryl-2-benzyl-1,2- dihydronaphtho[1,2-e][1,3]oxazine-3-one, and trans-1,3-diaryl-1H-naphtho[1,2-e] [1,3]oxazine-2(3H)-carbaldehyde were selectively synthesized via a chemoselective reaction of 1,3-diaryl-2,3-dihydro-1H-naphtho[1,2-e][1,3]oxazines and triphosgene or triethyl orthoformate, respectively, induced by different low-valent titanium systems. This method has the advantages of short reaction time (15 min), convenient manipulation, and high chemoselectivity.