Reductions sodium iodide

REDUCTION WITH ZINC AND SODIUM IODIDE Reductive Cleavage of Sulfonates to Hydrocarbons [700]... 

Olefin inversion. This reaction can be accomplished by conversion of the olefin into the ntc-dichloride (CI2 in CH2CI2) or nic-bromochloride (HCl-NBS in CH2CI2) followed by sodium iodide reduction in DMF as formulated (equation I). The first reaction involves rr wts-add tion, whereas the second is a... 

This is the most efficient way of introducing a A -double bond into a 5a-3-keto corticoid. Alternatively the 2,4-dibromo compound can be treated with sodium iodide in acetone (preferably in the presence of iodoacetone) followed by reduction of the resulting 2-iodo-A -3-ketone to the A -3-ket-... 

It is not possible to use zinc for reductive debromination in the presence of (x-halo ketones and for transformations involving these intermediates, sodium iodide has been used. ° In some instances, e.g. 5,6-dihalo-3-ketones, iodide does not always give a completely halogen-free product, and zinc does not give clean debromination. The use of chromous chloride has proved advantageous in such cases and is the reagent of choice for vicinal dichlorides, which are inert to iodide ... 

The ready reduction of iodohydrins is utilized in the Cornforth reaction for preparing olefins from epoxides. Here the opening and reduction are carried out in one step by treatment of the epoxide, in an acetic acid-sodium acetate buffer, with sodium iodide and zinc. A less common use of iodohy-drin reduction is illustrated in the synthesis of the diene (127) ... 

Disulfonate esters of vicinal diols sometimes undergo reductive elimination on treatment with sodium iodide in acetone at elevated temperature and pressure (usually l(X)-200°). This reaction derived from sugar chemistry has been used occasionally with steroids, principally in the elimination of 2,3-dihy-droxysapogenin mesylates. The stereochemistry of the substituents and ring junction is important, as illustrated in the formation of the A -olefins (133) and (134). 

Sodium iodide in trifluoroacetic anhydride reacts with epoxides to form the corresponding alkenes in high yields [39] The reduction is stereospecific and generates olefins of the same geometry as the starting epoxides [39]... 

As inert as the C-25 lactone carbonyl has been during the course of this synthesis, it can serve the role of electrophile in a reaction with a nucleophile. For example, addition of benzyloxymethyl-lithium29 to a cold (-78 °C) solution of 41 in THF, followed by treatment of the intermediate hemiketal with methyl orthoformate under acidic conditions, provides intermediate 42 in 80% overall yield. Reduction of the carbon-bromine bond in 42 with concomitant -elimination of the C-9 ether oxygen is achieved with Zn-Cu couple and sodium iodide at 60 °C in DMF. Under these reaction conditions, it is conceivable that the bromine substituent in 42 is replaced by iodine, after which event reductive elimination occurs. Silylation of the newly formed tertiary hydroxyl group at C-12 with triethylsilyl perchlorate, followed by oxidative cleavage of the olefin with ozone, results in the formation of key intermediate 3 in 85 % yield from 42. 

Intermediate 10 must now be molded into a form suitable for coupling with the anion derived from dithiane 9. To this end, a che-moselective reduction of the benzyl ester grouping in 10 with excess sodium borohydride in methanol takes place smoothly and provides primary alcohol 14. Treatment of 14 with methanesulfonyl chloride and triethylamine affords a primary mesylate which is subsequently converted into iodide 15 with sodium iodide in acetone. Exposure of 15 to tert-butyldimethylsilyl chloride and triethylamine accomplishes protection of the /Mactam nitrogen and leads to the formation of 8. Starting from L-aspartic acid (12), the overall yield of 8 is approximately 50%, and it is noteworthy that this reaction sequence can be performed on a molar scale. 

Sodium cyclopentadienide, 41, 96 Sodium dichromate for oxidation of alkylarcncs to aromatic carboxylic acids, 43, 80 Sodium iodide, in conversion of 2,4-di-nitrochlorobenzene to 2,4-dinitro-iodobenzene, 40, 34 reduction of peroxide with, 41,... 

Among the recently (as of 2003) described reactions of such quaternary salts, reduction to dihydroquinoxalines has been exemplified toward the end of Section 2.2.4 treatment of the diquaternary compound, 1,4,6,7-tetramethylquinox-alinediium bis(tetrafluoroborate) (215), with sodium iodide gave a well-characterized product that appears in X-ray studies to have the cation radical structure (216) ""° and a fundamental spectrophotometric study on the addition of hydroxyl and methoxyl ions to the 1-methylquinoxalinium cation has been reported. ... 

Iodotrimethylsilane generated in situ from chlorotrimetylsilane and sodium iodide effects the reduction of nitroalkenes into ketones at 0 °C. This method is useful for the conversion of nitro steroids or nitro terpenoids to the corresponding ketones (Eq. 6.24).43... 

Di-w -pentyl Ether [TMSI-Catalyzed Reduction of an Aldehyde to a Symmetrical Ether].314 A mixture of sodium iodide (0.15 g, 1 mmol), 1-pentanal (1.06 mL, 10 mmol), and trimethylsilyl chloride (2.0 mL, 15.4 mmol) was stirred in MeCN (5.0 mL) at room temperature for 10 minutes, after which 1,1,3,3-tetramethyldisiloxane (TMDO, 1.79 mL, 10 mmol) was added. When the exothermic reaction had ended (30 minutes), a solution of 2.5 N HF in MeOH (30 mL) was added to the reaction mixture, which was then refluxed for 5 minutes. Work-up was carried out by diluting the solution with CH2CI2 (40 mL), washing with water (30 mL) and saturated aqueous NaHC03 solution (20 mL), drying, and evaporating the solvents. Crude di-n-pentyl ether was purified by distillation 0.65 g (84%) bp 185-1897760 Torr. 

One-electron reduction of unsaturated a,8-diketones may sometimes generate a diene structure and initiate condensation. Thus, triazoledions (TAD) pass into tetraazabicyclooctanetetraones (TABO). Naphthalene-sodium (ca. 1 mol%), sodium metal, or even sodium iodide efficiently catalyzes the reaction. Tetracyanoethyene and lead tetraacetate retard it. Consequently, the condensation has a chain character (Borhani and Greene 1986 Scheme 7.30). 

Cerium(III) iodide prepared in situ from an aqueous solution of ceric sulfate first by reduction with sulfur dioxide followed by sodium iodide reduced a-bromoketones to ketones in 82-96% yields [212]. 

Selective reduction of a-chloro and a-bromo ketones can be achieved by treatment with sodium iodide and chlorotrimethylsilane in acetonitrile at room temperature [224],... 

Chlorine was replaced by hydrogen in 2,4,6-trinitrochlorobenzene by heating with sodium iodide and acetic acid at 100° without the reduction of any nitro group [223]. 

Chemical deoxygenation of sulfoxides to sulfides was carried out by refluxing in aqueous-alcoholic solutions with stannous chloride (yields 62-93%) [186 Procedure 36, p. 214), with titanium trichloride (yields 68-91%) [203], by treatment at room temperature with molybdenum trichloride (prepared by reduction of molybdenyl chloride M0OCI3 with zinc dust in tetrahydrofuran) (yields 78-91%) [216], by heating with vanadium dichloride in aqueous tetrahydrofuran at 100° (yields 74-88%) [216], and by refluxing in aqueous methanol with chromium dichloride (yield 24%) [190], A very impressive method is the conversion of dialkyl and diaryl sulfoxides to sulfides by treatment in acetone solutions for a few minutes with 2.4 equivalents of sodium iodide and 1.2-2.6 equivalents of trifluoroacetic anhydride (isolated yields 90-98%) [655]. 

Sodium iodide is proposed as a good supporting electrolyte for the dimerization of enol ethers in methanol [41], The electrolyte is readily oxidised to iodine so that the first reaction of the vinyl ether will be iodomethoxylation [43], Since the electrochemical reaction is canied out in an undivided cell, reduction of the iodo intermediate at the cathode can give the dimeric product (see p. 99). 

Reticuline (38), one of the most important intermediates in the biosynthesis of opium alkaloids, has been synthesized in racemic form (Scheme 7) (78). 6-Methoxy-7-benzyloxyisoquinoline (39), prepared from O-benzylisovanillin via a modified Pomeranz-Fritsch isoquinoline synthesis, was treated with benzoyl chloride and potassium cyanide to obtain Reissert compound 40. Alkylation of the anion generated from 40 with 3-benzyloxy-4-methoxybenzyl chloride gave the corresponding 1-substituted Reissert compound 41 which was hydrolyzed in alkaline medium to 1-benzylisoquinoline derivative 42. Quatemarization of 42 with methyl iodide followed by sodium borohydride reduction and debenzylation led to ( )-reticuline (38) in about 25% overall yield from 39. 

In the rings containing sulfur, reduction of sulfoxides of phenoxathiin and thianthrene can be performed in excellent yield with the aluminium chloride/sodium iodide or zinc dust/l,4-dibromobutane systems <1996CHEC-II(6)447>. 

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