- A mild and highly chemoselective iodination of alcohol using polymer supported DMAP
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The synthesis of organic compounds using polymer supported catalysts and reagents, where the required product is always in solution, has been of great interest in recent years, both in industries and academia especially in pharmaceutical research. Here, a simple and efficient method for conversion of alcohols into their iodides in high yield using polymer supported 4-(Dimethylamino)pyridine (DMAP) is described. Polymer supported DMAP is used in catalytic amount and is recovered and reused several times. Additionally, this method is highly chemoselective. [Figure not available: see fulltext.]
- Das, Diparjun,H Anal, Jasha Momo,Rokhum, Lalthazuala
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p. 1695 - 1701
(2017/03/08)
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- A mild method for the replacement of a hydroxyl group by halogen. 1. Scope and chemoselectivity
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α-Chloro-, bromo- and iodoenamines, which are readily prepared from the corresponding isobutyramides have been found to be excellent reagents for the transformation of a wide variety of alcohols or carboxylic acids into the corresponding halides. Yields are high and conditions are very mild thus allowing for the presence of sensitive functional groups. The reagents can be easily tuned allowing therefore the selective monohalogenation of polyhydroxylated molecules. The scope and chemoselectivity of the reactions have been studied and reaction mechanisms have been proposed.
- Munyemana, Fran?ois,George, Isabelle,Devos, Alain,Colens, Alain,Badarau, Eduard,Frisque-Hesbain, Anne-Marie,Loudet, Aurore,Differding, Edmond,Damien, Jean-Marie,Rémion, Jeanine,Van Uytbergen, Jacqueline,Ghosez, Léon
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p. 420 - 430
(2015/12/31)
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- Simple synthesis of fresh alkyl iodides using alcohols and hydriodic acid
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A simple synthesis of fresh alkyl iodides using alcohols and hydriodic acid (HI) is reported. The alkyl iodides were obtained in quick and easy work-up with good to excellent yields (66-94%) and very high purities (97-99%). Freshly prepared iodomethane and 1-iodobutane were applied to synthesize biologically relevant 3,7-dimethyladenine and 9-butyladenine, which were characterized thoroughly using 1D and 2D NMR, individually.
- Klein, Suzane M.,Zhang, Cungen,Jiang, Yu Lin
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p. 2638 - 2641
(2008/09/19)
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- Direct halogenation of alcohols and their derivatives with tert-Butyl halides in the ionic liquid [pmIm]Br under sonication conditions - A novel, efficient and green methodology
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A novel halogenating reagent system for direct halogenation of alcohols has been developed. tert-Butyl bromide, chloride and iodide in combination with the ionic liquid [pmIm]Br have been found to convert alcohols into the corresponding bromides, chlorides and iodides under sonication conditions (or heating) in good yields. Although a variety of primary and secondary alcohols participated in this reaction without any difficulty, tertiary alcohols remained inert. Several alcohol derivatives such as OTMS, OTBDMS, OAc, OTS and OTHP are also transformed into the corresponding halides in one-pot fashion by this procedure. A plausible rationale for this transformation is also presented. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005.
- Ranu, Brindaban C.,Jana, Ranjan
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p. 755 - 758
(2007/10/03)
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- Direct bromination and iodination of non-activated alkanes by hypohalite reagents
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The direct functionalisation of alkanes through bromination and iodination has been successfully achieved. The combination of stoichiometric mixtures of elemental halogen and sodium alkoxides leads to the formation of alkyl hypobromites and hypoiodites as reagents. The halogenation occurs without external photostimulation under thermal reaction conditions. Georg Thieme Verlag Stuttgart.
- Montoro, Raul,Wirth, Thomas
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p. 1473 - 1478
(2007/10/03)
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- Direct Iodination of Alkanes
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(Matrix presented) A cheap and efficient iodination of hydrocarbons can be achieved by generating tert-butyl hypoiodite from iodine and sodium tert-butoxide. The alkane is reactant and solvent, and this metal-free process provides a clean solution for their direct iodination.
- Montoro, Raul,Wirth, Thomas
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p. 4729 - 4731
(2007/10/03)
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- Bicyclic imidazolyl derivatives as phosphodiesterase inhibitors, pharmaceutical compositions and method of use
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The present invention provides for compounds having the following Formulae I-III, and The compounds of the present invention are useful in the treatment of a variety of disease such as glaucoma, sexual dysfunction, asthma and cardiovascular disorders such as stable-, unstable- and variant-angina, hypertension, pulmonary hypertension, congestive heart failure, atherosclerosis, and thrombosis.
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- Primary and secondary 5-(alkyloxy)thianthrenium perchlorates. Characterization with 1H NMR spectroscopy, reactions with iodide and bromide ion, and thermal decomposition in solution
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A series of 5-(alkyloxy)thianthrenium perchlorates has been made in which the alkyl group is primary (1a-1p) and secondary (2a-2g). Preparations were carded out by reaction of the corresponding alkanol with thianthrene cation radical perchlorate in CH2Cl2 solution followed by precipitation of the perchlorate salt with dry ether. 1H NMR spectroscopy reveals that the presence of a stereogenic center in the alkyl group causes inequivalence in the ordinarily paired protons (e.g., H-4, H-6) of the thianthrenium ring. Reaction of iodide and bromide ion with primary alkyl-group compounds (e.g., methyl, ethyl, propyl, butyl) gave the alkyl halide in very good yield and by a second-order kinetic displacement. The second product was thianthrene 5- oxide (ThO). Rate constants for some of these reactions are reported. Reaction of secondary alkyl group compounds (e.g., 2-propyl, 2-pentyl, 2- hexyl, and 3-hexyl) with iodide ion gave good yields of alkyl iodide but also increasing evidence for a side reaction at the sulfonium sulfur, leading to I2, thianthrene, and secondary alkanol. Decomposition of some compounds at 100°C in solution (acetonitrile or 1,2-dichloroethane) was studied and gave alkene(s) and ThO.
- Zhao, Wenyi,Shine, Henry J.
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p. 695 - 702
(2007/10/03)
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- Radical reactions in the radiolysis of cyclopentane
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The end products produced in the γ-radiolysis of cyclopentane have been measured at very low total doses (25-50 krad). Iodine scavenging techniques in solutions of 0.1-30 mM were used to elucidate radical yields and reaction mechanisms. The yields of the main radical species were found to be as follows: cyclopentyl, 4.9; 1-pentyl, 0.2; 3-cyclopentenyl, 0.07; H atom, 1.3 radical/100 eV. The change in yields from neat cyclopentane to 0.1 mM iodine solution suggests that about 79% of the cyclopentyl radicals escape the spur and react in the bulk medium with a disproportionation to combination ratio of 0.97. Radical precursors account for about 50% of the total end product yield, which is much smaller than found in the radiolysis of cyclohexane or cyclooctane. The radiolysis mechanism for cyclopentane is discussed and compared to those for cyclohexane and cyclooctane.
- Wojnarovits,LaVerne
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p. 3168 - 3172
(2007/10/02)
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- Chiral Organometallic Reagents, XI. Stereoselective Exchange of Diastereotopic Iodine Atoms by Magnesium in 3-Alkoxy-1,1-diiodoalkanes
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α-Iodoalkylmagnesium species were generated by reaction of 3-oxygenated 1,1-diiodoalkanes with isopropylmagnesium halides at -78 deg C.The resulting magnesium carbenoids were found to be configurationally stable at temperatures up to -20 deg C and were trapped by benzaldehyde or allyl iodide at low temperatures.Stereoselectivity on exchange of the diastereotopic iodine atoms in 3 was found to be low. - Key Words: 1-Iodoalkylmagnesium reagents / Stability, configurational
- Hoffmann, Reinhard W.,Kusche, Andreas
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p. 1311 - 1316
(2007/10/02)
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- Radical Cations from Alkyl Iodides in Aqueous Solution
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Radical cations RI(1+) and (RIIR)(1+) are generated upon OH radical-induced oxidation of alkyl iodides in acidic (pHOH-adduct.Although alkyl iodide radical cations have been reported to exist in a solid, low-temperature matrix, they have so far not been detected in the liquid, particularly the aqueous phase.Both radical cations establish an equilibrium: .For R=Me the stability constant of the 2?-1?* three-electron-bonded species has been estimated to K>/=5E4 mol-1dm3. (RIIR)(1+) exhibits a strong optical absorption band in the visible; λmax is red-shifted with increasing electron-releasing power of R and ranges from 4115 nm (R=Me) to 470 nm (R=s-C4H9).The molecular radical cation absorbs in a comparatively much narrower range from 310-320 nm.It is suggested that it exists as (RIOH2)(1+), i.e. as an associate with one water molecule.The alkyl iodide radical cations are strong oxidants. (MeIIMe)(1+), for example, oxidizes I(1-) and Me2S with rate constant values of 7.7E9 mol-1dm3s-1 and 3.6E9 mol-1dm3s-1, respectively.
- Mohan, Hari,Asmus, Klaus-Dieter
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p. 1795 - 1800
(2007/10/02)
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- NEW PREPARATION OF ALKYL IODIDES FROM THE CORRESPONDING ALCOHOLS
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It is shown that alkyl iodides can be obtained from the corresponding alkyl α-chloroethyl carbonate and NaI or by direct reaction between the alcohol, α-chloroethyl chloroformate and NaI.
- Brunet, J. J.,Laurent, H.,Caubere, P.
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p. 5445 - 5446
(2007/10/02)
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- Hydroxyvitamin D2 compounds and process for preparing same
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This invention relates to hydroxylated derivatives of vitamin D2, to processes for preparing such compounds, to intermediates utilized in such processes and to certain isotopically labelled vitamin D2 compounds. The vitamin D2 derivatives would find application in the treatment of or prophylaxsis for various disease states characterized by calcium and phosphorous imbalances and as a substitute for vitamin D3 and its metabolites in their various applications.
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- Antibiotics and derivatives thereof having β-lactamase inhibitory activity and production thereof
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A novel antibiotic substance of the formula STR1 wherein R1 is CH3 and R2 is --CH2 --CH2 -- or R1 is H and R2 is --CH=CH--; and R3 represents hydrogen, lower alkyl or triphenylmethyl, and including the salts of the compound of formula (I) wherein R3 is hydrogen, said antibiotic substance having strong antibiotic activity and β-lactamase inhibiting effect, and a method for producing the same by aerobic cultivation of Streptomyces A271.
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- Reduction of Sulfonic Acids and Related Organosulfur Compounds with Triphenylphosphine-Iodine System
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Arenesulfonic acids, their sodium salts, and alkyl arenesulfonates can be reduced readily to the corresponding arenethiols quantitatively by treatment with a mixture of triphenylphosphine and a catalytic amount of iodine, while alkanesulfonic acids, sulfinic acids, disulfides, thiosulfonic S-esters, and sulfonates are also readily reduced to the corresponding thiols similarly.Upon treatment with a mixture of triphenylphosphine and excess iodine, however, these aliphatic sulfur compounds are converted eventually to the corresponding alkyl iodides.The relative reactivities of these sulfonyl derivatives in the reaction with the triphenylphosphine-iodine system are the following.Aromatic series: ArSO2Cl, ArSO2SAr' > ArSO2H > ArSO3R > ArSO3-HNBu3+ (or PyH+) > ArSO3H > ArSO2SO2Ar >> ArSO2CH2C(CH3)3, ArSO3Ar'.Aliphatic series: RSO2Cl, RSO2SR', RSO2-HNBu3+ > RSO3-HNBu3+ > RSSR, RSO2H > RSO3H > RSH > RSO3R'.In these reactions, the arenesulfonic acids bearing electron-donating substituents can be reduced more readily than those having electron-withdrawing substituents.
- Oae, Shigeru,Togo, Hideo
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p. 3802 - 3812
(2007/10/02)
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- REDUCTION OF ORGANIC SULFONIC ACIDS, SODIUM SULFONATES, AND SULFONIC ESTERS TO THE CORRESPONDING DISULFIDES WITH POLYPHOSPHORIC ACID DERIVATIVES, POTASSIUM IODIDE AND TETRABUTYLAMMONIUM IODIDE SYSTEM.
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Organic sulfonic acids, sodium sulfonates, and alkyl sulfonates were readily reduced to the corresponding disulfides in moderate yields upon treatment with a mixture of a polyphosphoric acid derivative and iodide. In these reactions, formation of mixed anhydrides each having a P-O-S linkage is the key step, and subsequent attack of iodide on the sulfur atom gives the corresponding sulfonyl iodides which are reduced further exothermally to the disulfides with the hydrogen iodide. Actually, p-toluenesulfonyl chloride was isolated in the reaction of p-toluenesulfonic acid and polyphosphoric acid derivatives with chloride ion. The competitive reduction of various aromatic sulfonic acids reveals that an aromatic sulfonic acid bearing an electron-donating para-substituent is more readily reduced to the disulfide than that which has an electron-withdrawing para-substituent.
- Oae,Togo
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p. 3813 - 3817
(2007/10/02)
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- Excited-State ? Succimidyl and Glutarimidyl Radicals: Reversible Ring Opening
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The free-radical isomerization of N-bromosuccinimide to β-bromopropionyl isocyanate has been examined.Of the two varieties of succinimidyl radical (S? or S?), only the ? excited state undergoes the ring opening to the β propionyl isocyanatyl radical.The conversion optimally takes place in >95percent yield.The dependence of NBS concentration along with results obtained from deuterium labeling studies indicate that the ring opening of S? is a reversible process.This explains the failure of N-chlorosuccinimide to produce β-chloropropionyl isocyanate, as well as the increase in ring-opened product for N-bromosuccinimides upon methyl substitution at the 2- and/or 3-position of the succinimidyl ring, since the open-chain radical intermediates are more stable.In the N-bromoglutarimide system, methyl groups on the 2-position are required for the glutarimidyl radicals to undergo the isomerization, ultimately producing isocyanates.The radical-chain nature of these systems is confirmed.
- Tlumak, Robert L.,Day, James C.,Slanga, Joseph P.,Skell, Philip S.
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p. 7257 - 7267
(2007/10/02)
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