An efficient synthesis of vinylogous carbamates from alkyl azides

An efficient one-pot synthesis of vinylogous carbamates is reported starting from alkyl azides by using NH₄Cl/Zn dust.     

Indium-mediated mild and efficient one-pot synthesis of alkyl phenyl selenides

A mild and convenient one-pot process for synthesizing alkyl phenyl selenides is developed using indium metal. The reaction shows the selectivity for tert-alkyl, benzylic, and allylic halides over primary and secondary alkyl halides.     

Electronic and steric effects on the intramolecular Schmidt reaction of alkyl azides with secondary benzyl alcohols

The intramolecular Schmidt reaction of simple azido secondary benzyl alcohols has been realized for the first time. Investigation of the electronic and steric effects of the substrates on the product outcome was conducted. Unique intramolecular Schmidt rearrangements were observed with the formation of a cinnamaldehyde derivative and aryl aldehydes, respectively. Using this protocol, an efficient synthesis of dihydrobenzotriazine derivatives was achieved. Moreover, a practical approach to 2-aryl-1-pyrrolines was also accessed.     

A fast and efficient method for the preparation of aryl azides using stable aryl diazonium silica sulfates under mild conditions

An efficient, fast, and straightforward procedure for the synthesis of aromatic azides using aryl diazonium silica sulfates and sodium azide at room temperature under mild conditions is described. The use of inexpensive materials, simple and clean work-up, short reaction times and good yields are advantages of this method.     

Practical and general method for the direct synthesis of alkyl fluorides from alcohols under mild conditions: a reinvestigation

Abstract  In contrast to the results presented in a previous report, the direct conversion of alcohols to alkyl fluorides with triphenylphosphine and potassium fluoride in CCl₄/DMF under mild conditions failed. Graphical Abstract        

Conversion of tertiary alcohols to tert-alkyl azides by way of quinone-mediated oxidation-reduction condensation using alkyl diphenylphosphinites

A novel method for the preparation of alkyl azides from alcohols by way of oxidation-reduction condensation is described. In this reaction, the sterically-hindered tert-alkyl phosphinites that are prepared from the corresponding alcohols are converted into tert-alkyl azides with almost complete inversion of their stereochemistry: the obtained alkyl azides are then successfully reduced to afford the corresponding amines on treatment with LiAlH₄, thus, a versatile method for the preparation of chiral amines from the corresponding chiral alcohols is established.     

A novel and efficient synthesis of alkyl thiocyanates from alkyl halides in water using phase transfer catalysts

1,4-Bis(triphenylphosphonium)-2-butene dichloride(BTPBDC) and 1,4-bis(triphenyl phosphonium)-2-butene dithiocyanate (BTPBDT) were prepared and used as phase-transfer catalysts.Alkyl halides were converted efficiently to the corresponding alkyl thiocyanates under mild reaction conditions in water.No evidence for the formation of isothiocyanates as by-product of the reaction was observed.     

3,4,5-Trifluorobenzeneboronic acid: a mild and versatile catalyst for the one-pot synthesis of acyl azides from carboxylic acids

Acyloxyboron intermediates generated from carboxylic acids and 3,4,5-trifluorobenzeneboronic acid react with sodium azide to furnish the corresponding acyl azides in moderate to good yields.     

The rapid and efficient synthesis of disulfides from alkyl and acyl halides

Various symmetrical dialkyl and diacyl disulfides are prepared easily in high yields from the corresponding alkyl and acyl halides under mild and nonaqueous conditions using N,N′-dibutyl-N,N,N′,N′-tetramethyl-ethylenediammonium tetrahydroborate (BTMETB) or N,N′-dibenzyl-N,N,N′,N′-tetramethylethylenediammonium tetrahydroborate (BZTMETB) and elemental sulfur. The quaternary diammonium borohydrides were easily prepared by treatment of the corresponding quaternary diammonium chloride or bromide with alkaline solution of sodium borohydride at room temperature. Correspondence: Mahmood Tajbakhsh, Department of Chemistry, Mazandaran University, Babolsar, Iran.     

A facile and convenient method for synthesis of alkyl thiocyanates under homogeneous phase transfer catalyst conditions

A simple and environmentally friendly method is described for the efficient conversion of alkyl halide to alkyl thiocyanate using tetrabutylammonium bromide （TBAB） as a phase transfer catalyst. The reactions occur in water and furnish the corresponding alkyl thiocyanate in high yields. No evidence for the formation of isothiocyanates as by-product of the reaction was observed and the products were obtained in pure form without further purification.     

Unexpected conversion of alkyl azides to alkyl iodides and of aryl azides to N-tert-butyl anilines

In the presence of tert-butyl iodide, alkyl azides are converted into the corresponding iodides at room temperature, whereas, N-t-Bu anilines are obtained from aryl azides under the same experimental conditions. A mechanism is proposed to explain this unusual reactivity.     

An efficient synthesis of substituted alkyl acrylates using α-keto amides

The addition of α-keto amides as a NH-acid to alkyl propiolates and dialkyl acetylenedicarboxylates in the presence of a catalytic amount of triphenylphosphine gives the corresponding substituted alkyl acrylates.     

An efficient and convenient synthesis of pentasubstituted pyrroles from alkyl acetoacetates,dialkyl acetylenedicarboxylates,and amines

A simple and efficient synthesis of pentasubstituted pyrroles has been developed using a one-pot, two-step reaction. The synthesis of a series of 4-hydroxypenta-1,3-diene-tricarboxylates from alkyl acetoacetates and dialkyl acetylenedicarboxylates in the presence of K₂CO₃, followed by cyclization with amines, gave the corresponding pyrroles in excellent yields.     

Convenient synthesis of sulfonyl azides using PEG-400 as an efficient and eco-friendly reaction medium

Sulfonyl azides have efficiently been synthesized via a convenient and environmentally benign procedure, in which sulfonyl chlorides undergo nucleophilic substitution reaction with sodium azide in PEG-400 under mild conditions. The sulfonyl azides were obtained in 84–97% isolated yields.

     

A mild, one-pot synthesis of disubstituted benzimidazoles from 2-nitroanilines

A one-pot synthesis of disubstituted benzimidazoles from 2-nitroanilines is described. Hydrogenation of N-substituted 2-nitroanilines with palladium on carbon as catalyst in the presence of trimethyl orthoformate and catalytic pyridinium p-toluenesulfonate (PPTS) at room temperature provided good to excellent yields of the corresponding disubstituted benzimidazoles.     

Application of vinylogous carbamates and vinylogous aminonitriles to the regiospecific synthesis of uniquely functionalized pyrroles and quinolones

Pyrroles and quinolones represent core structures, which are routinely found in both natural and synthetic bioactive substances. Consequently, the development of efficient and regiospecific methods for the preparation of such heterocycles with unique functionality is of some importance. We describe herein the regiospecific synthesis of 1,2,3,4-tetrasubstituted pyrroles containing polar substituents and such products are prepared from vinylogous carbamates and vinylogous aminonitriles. We also describe the regiospecific synthesis of 3-aryl containing 1,3,6-trisubstituted quinolones from vinylogous carbamates. The use of an amine exchange reaction to prepare precursors for the pyrrole and quinolone forming cyclizations represents a key factor in the strategy.     

An efficient synthesis of substituted alkyl acrylates using α-keto amides

The addition of α-keto amides as a NH-acid to alkyl propiolates and dialkyl acetylenedicarboxylates in the presence of a catalytic amount of triphenylphosphine gives the corresponding substituted alkyl acrylates.     

A new reagent for the efficient synthesis of disulfides from alkyl halides

Benzyltriethylammonium tetracosathioheptamolybdate [(C₆H₅CH₂N(Et)₃)₆Mo₇S₂₄] has been found to be a superior sulfur transfer reagent for the conversion of alkyl halides to the corresponding disulfides in excellent yields under very mild reaction conditions.     

Simple and facile method for the preparation of vinyl azides

A synthetic utility of [bis(trifluoroacetoxy)iodo]benzene on α,β-unsaturated carboxylic acid is described. This is the first example of preparation of vinyl azide using α,β-unsaturated carboxylic acids directly by using hypervalent iodine reagent. The advantage of this protocol is characterized with non-toxicity of starting material and shorter reaction times to obtain good preparative yields. The method is also useful for the preparation of acyl azides.     

LiClO4 catalyzed mild and efficient method for the synthesis of thiiranes from oxiranes

Oxiranes are efficiently converted to the corresponding thiiranes by potassium thiocyanate in the presence of catalytic amounts of LiClO₄ with excellent yields under mild and nonaqueous conditions. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:97–99, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20376