A simple and efficient bromoformyloxylation and bromoacetoxylation reaction using TsNBr2

Bromoformyloxylation and bromoacetoxylation of olefins proceed smoothly and instantaneously in the presence of N,N-dibromo-p-toluene sulfonamide without any catalyst. The one step reactions can be carried out with all kinds of olefins in high yield and high regio and stereoselectivities.     

A simple and efficient synthesis of 2-substituted benzothiazoles catalyzed by H_2O_2/HCl

A simple and efficient procedure for the synthesis of substituted benzothiazoles through condensation of 2-aminothiophenol with aromatic aldehydes in the presence of H_2O_2/HCl system in ethanol at room temperature is described.The target compounds have been characterized by ~1H NMR,~(13)C NMR,IR and MS.Short reaction time,easy and quick isolation of the products,and excellent yields are the main advantages of this procedure.     

Synthesis of 4- and 5-substituted 1-hydroxyimidazoles through directed lithiation and metal-halogen exchange.

Electrophiles were introduced regioselectively at the 5-position of 1-(benzyloxy)imidazole by lithiation at C-5 after protection of C-2 with a chloro or a trimethylsilyl group. Subsequent treatment with an electrophile afforded 5-substituted 1-(benzyloxy)-2-chloroimidazoles 8-13 and 5-substituted 1-(benzyloxy)imidazoles 3-5, the 2-(trimethylsilyl) group being lost during workup. Electrophiles were introduced regioselectively at the 4-position of 1-(benzyloxy)imidazole by bromine-lithium exchange of 4-bromo-2-chloro-1-(benzyloxy)imidazoles, protected at C-5 with chloro or trimethylsilyl groups, followed by reaction with an electrophile. The 5-(trimethylsilyl) group was removed via base-catalyzed desilylation. Chlorine at C-2 and O-benzyl groups were removed by palladium-catalyzed hydrogenolysis.     

A simple and highly efficient method for the synthesis of chalcones by using borontrifluoride-etherate

Chalcones are secondary metabolites of terrestrial plants, precursors for the biosynthesis of flavonoids and exhibit various biological activities. Condensation of substituted acetophenones (2a-12a) with various aromatic aldehydes (1b-7b) in the presence of BF₃-Et₂O at room temperature gave chalcones in 75-96% yield.     

A simple and efficient synthesis of 2-substituted benzothiazoles catalyzed by H_2O_2/HC1

A simple and efficient procedure for the synthesis of substituted benzothiazoles through condensation of 2-aminothiophenol with aromatic aldehydes in the presence of H₂O₂/HCl system in ethanol at room temperature is described. The target compounds have been characterized by ¹H NMR, ¹³C NMR, IR and MS. Short reaction time, easy and quick isolation of the products, and excellent yields are the main advantages of this procedure.     

A simple and efficient synthesis of 3-substituted derivatives of pentane-2,4-dione

A novel and efficient method of synthesis of 3-substituted derivatives of pentane-2,4-dione is proposed, wherein cheaper and easily accessible chloro derivatives are conversed into more reactive iodo derivatives. The method is based on the Finkelstein reaction for which the literature suggests highly polar organic solvents as ideal reaction media. In the presented work, the use of industrially used ketones, especially methyl isobutyl ketone, is proposed. The use of MIBK as a solvent additionally allows an azeotropic removal of water from the reaction mixture, enabling the application of moisture sensitive alkylating agents i.e. (3-chloropropyl)trimethoxysilane. The obtained products are isolated through distillation, which does however not allow the separation of C-alkylation products from O-alkylation ones. The products not containing water-sensitive substituents were isolated as copper complexes. The pure product of C-alkylation was obtained by decomposition of the copper complex with a hydrochloric acid solution and extraction of the formed ligand to an organic phase i.e. hexane. The obtained ligand can be further purified by distillation. Presented at the 35th International Conference of the Slovak Society of Chemical Engineering, Tatranské Matliare, 26–30 May 2008.     

A simple and efficient method for the synthesis of Erlenmeyer azlactones

We have recently developed a novel and efficient method for synthesising Erlenmeyer azlactones under mild and rapid conditions. The reaction is performed by reacting 2-phenyl-5-oxazolone with an aldehyde in dichloromethane using alumina as a catalyst. The materials react instantly at room temperature, negating the need for high temperatures and long reaction times. We have successfully used this method for both aliphatic, aromatic and heteroaromatic aldehydes, synthesising previously unmade Erlenmeyer azlactones in moderate to high yields.     

A simple and efficient synthesis of 2-alkylazulenes

The annulation method based on 2H-cyclohepta[b]furan-2-ones was applied for the synthesis of 2-alkylazulenes; 2-R-azulene (R = Et, i-Pr, n-Pr, i-Bu). Tropolone p-toluenesulfonate was used as a starting compound. By the two step synthesis, 1-carboxylic-3-cyanoazulene derivatives were obtained. Treatment of 1-carboxylic-3-cyanoazulene derivatives with aq H₂SO₄ resulted in decarboxylation and elimination of cyano group to give 2-alkylazulenes in good yields.     

A novel and simple benzannulation reaction using the potassium salt of methyl mercaptoacetate for the synthesis of 3-aryl-2-methoxycarbonylacridines

A new benzannulation methodology has been developed and applied to the synthesis of 3-aryl-2-methoxycarbonylacridines.     

A novel method for the synthesis of 5-substituted 1H-tetrazole from oxime and sodium azide

A simple and efficient protocol is developed for the synthesis of 5-substituted 1H-tetrazoles from various oximes and sodium azide (NaN₃) by using copper acetate as a catalyst.     

从尿核苷合成异胞苷衍生物的简便有效方法

本文报道从5'-O-磺酰基-2',3'-O-异亚丙基尿核苷通过一步法合成N-烷基2',3'-O-异亚丙基异胞苷和从5'-O-对甲苯磺酰基尿核苷合成5'-脱氧-5'-异丙氨基尿核苷。并对以上产物形成的机制作了探讨。     

A rapid and general method for the asymmetric synthesis of 2-substituted pyrrolidines using tert-butanesulfinamide

A new method for the asymmetric synthesis of 2-substituted pyrrolidines in three steps from commercially available starting materials is described. Addition of the Grignard reagent prepared from 2-(2-bromoethyl)-1,3-dioxane to N-tert-butanesulfinyl aldimines proceeds in high yields and with good diastereoselectivities. The sulfinamide products are then cleanly converted into pyrrolidines in one step.     

An efficient and economical synthesis of 5-substituted 1H-tetrazoles via Pb(II) salt catalyzed [3+2] cycloaddition of nitriles and sodium azide

A simple, mild and efficient method is developed for the synthesis of 5-substituted 1H-tetrazoles. Out of three used Pb(II) catalysts, lead chloride (PbCl₂) has been found to be an efficient catalyst for [3+2] cycloaddition of NaN₃ with aromatic and aliphatic nitriles to afford 5-substituted 1H-tetrazoles. The catalyst is reusable up to four cycles with consistent activity. The cost effectiveness and easy availability of the catalyst, simple methodology, excellent yield and easy work-up are the additional advantages.     

An efficient one-pot four-step domino reaction for the synthesis of C2-substituted 3-methylcyclohex-2-enones

An efficient one-pot four-step domino reaction of substituted β-ketoesters has been optimized giving rise to a large panel of C2-substituted 3-methylcyclohex-2-enones, an important scaffold for the preparation of various initiators for cationic or radical cyclizations. The developed methodology is quite general and applicable to a wide range of β-ketoester substrates, allowing the introduction of various functionalities at the C2 position of the 3-methylcyclohex-2-enones, in good to excellent yields.     

A simple and efficient synthesis of 2-aryl-substituted benzimidazoles

Sodium hydrogen sulfite was used to promote condensation of o-phenylenediamine with aromatic aldehydes in dimethylformamide to obtain the corresponding 2-arylbenzimidazoles. The procedure is simple and convenient, and it implies inexpensive promoter and is characterized by short reaction time and easy purification of the final products. Published in Russian in Zhurnal Organicheskoi Khimii, 2008, Vol. 44, No. 6, pp. 872–874. The text was submitted by the authors in English.     

5-Endo-dig electrophilic cyclization of alpha-alkynyl carbonyl compounds: synthesis of novel bicyclic 5-iodo- and 5-bromofuranopyrimidine nucleosides

5-Endo-dig electrophilic cyclization of 5-alkynyl-2'-deoxyuridines with N-iodosuccinimide or N-bromosuccinimide in acetone at room temperature gives 3-(2'-deoxy-beta-D-ribofuranosyl)-5-halo-2,3-dihydrofuro[2,3-d]pyrimidin-2-ones that usually precipitate from the reaction mixture (86-74%).     

A simple and efficient method for the synthesis of amidophenols using iodine as catalyst under neat condition

A convenient and efficient one-pot synthesis of substituted amidophenols using iodine as catalyst at room temperature under neat condition is described.