Search

To develop the utilization of HI as an ‘old but new’ reagent, we found that the reaction of acetophenone analogues with HI gas proceeded to give an α-alkylated product, which is derived from the two ketone molecules. It was possible to conduct the reaction in solvent-free and various organic solvents under anhydrous conditions. From the investigation on the reaction mechanism, we proposed that HI acts as an acid and a reducing agent.

The reaction of 2-(arylamino)-1-(methylthio)-1-tosylethenes ( 4 ) with hydrogen iodide in refluxing toluene gave 3-tosyl-2-(tosylmethyl)quinoline derivatives ( 6 ) in good yields. In this reaction, hydrogen iodide dose not only reductively removes the methylthio group of 4 to form an intermediary 1-(arylamino)-2-tosylethene ( 5 ), but also serves as a protic catalyst for the subsequent dimeric cyclization of 5 to lead to the quinoline derivatives ( 6 ).

A mixture of hypophosphorous acid (H3PO2) and iodine in hot acetic acid reduces diaryl ketones quickly and aryl alkyl ketones slowly to the corresponding methylene derivatives. The active reducing agent is hydrogen iodide, generated by reaction between iodine and hypophosphorous acid.

A new efficient method for demethylation of aryl methyl ethers using iodocyclohexane in DMF under reflux condition is described.

The hydrogen iodide salt of 1,8-bis-(N-benzyl-N-methylamino)naphthalene was synthesised as an 89 / 11 ratio of diastereomers in good yield. The structure of the major ) diastereomer was determined by single crystal X-ray diffraction. The minor diastereomer is shown to be the meso-(RNSN) form by performing 1H NMR n.O.e studies on isotopically desymmetrized (HI salt). The half-life of interconversion of meso and dl forms is less than 2 minutes in CD2Cl2 at ambient temperature.

Peracetylated ester derivatives of N -acetyl neuraminic acid were reacted with hydrogen iodide in acetic acid to stereoselectively provide α-2-deoxy-2-hydrido analogs. The reaction proceeds through formation of an anomeric iodide which, in the presence of excess HI, is reduced to give an enol intermediate. Kinetic protonation of the intermediate enol gives a 3.4:1 α:β mixture of 2-deoxy-2-hydrido derivatives. Under thermodynamic conditions the α-anomer is formed exclusively.

Carbonylation of benzyl alcohol catalyzed by a palladium(0) complex and promoted by hydrogen iodide gives phenylacetic acid in excellent yields in aqueous systems. The catalysis is proposed to proceed through a benzylpalladium species formed by the oxidative addition of benzyl iodide, produced in situ by the interaction of benzyl alcohol with HI, to a Pd(0) species. Application of the carbonylation process to other arylmethanol analogs provided convenient means to prepare 3-isochromanone, 1,4-benzenediacetic acid, 2-hydroxybenzeneacetic acid and 2-naphthaleneacetic acid.

A mixture of hypophosphorous acid (H 3 PO 2 ) and iodine in acetic acid reduces a variety of substituted benzhydrols to the corresponding methylene derivatives in very high yields. The active reducing agent is hydrogen iodide generated by reaction between iodine and hypophosphorous acid.

Alkyl TBS ethers can be selectively cleaved in high yield in the presence of aryl TBS ethers employing either in situ generated hydrogen chloride or hydrogen iodide.

Treatment of terminal acetylene with in situ generated hydrogen iodide and followed by the reaction with cuprous cyanide provided a simple and regioselective transformation of acetylene into 2-substituted acrylonitrile in fair to good yields. © 1997 Elsevier Science Ltd.

A one-pot reaction of terminal alkynes with in situ generated hydrogen iodide and organozinc compounds in the presence of Pd(PPh3)4 provided a simple and useful method for the preparation of gem-disubstituted-alkenes.

Treatment of either 3- tert -butyl-2-adamantanol or 2-isopropenyl-2-methyladamantane with acid in the presence of a reducing agent (hydrogen iodide or tri- 2 -hexylsilane) yielded 2- tert -butyladamantane as the major or exclusive product. Both precursors gave the 2- tert - butyl-2-adamantyl cation at −78°C in FSO3H-SbF5-SO2ClF.

C-isoprenylation of phenols has been effected using a combination of isoprene and in situ generated iodotrimethylsilane or hydrogen iodide.

The conversion of alcohols into alkyl iodides is very often a useful and necessary organic transformation. We wish now to report a simple and efficient one-step method for the conversion of alcohols into iodides under mild conditions via treatment of the alcohols or their trimethylsilyl ethers with the interesting electrophilic reagent, trimethylsilyl iodide.' The two classical methods for this reaction are a) the use of red phosphorus and molecular iodine,3 and b) the reaction of alcohols with hydrogen iodide, usually generated in situ from alkali -iodide and acid. 4 Several newer methods have appeared recently which utilize a variety of phosphorus and boron derivatives and in which formation of a molecule containing a very stable phosphorus-oxygen double bond (phosphonate5 and phosphate6 derivatives) or a boron-oxygen single bond7 provides a large part of the driving force for the reaction. Finally, conversion of the alcohol into a good leaving group followed by nucleophilic attack by iodide ion forms the basis of several other recent techniques for this transformation.8

The phosphonium salt obtained by P-methylation of 2-diphenyl-phosphinotropone with methyl iodide was found to undergo C-7 addition by piperidine, and loss of hydrogen iodide, to give an acylsphosphorane which could be isolated; the regiospecificity of piperidine addition was proven by deuterium labeling at the troponoid ring.