Reduction by zinc

R. Mellon (19) but using anhydrous reagents. He obtained an oil that reacted exothermically with hydroxylamine (oxime of m.p. 135°) and that isomerized to 2-oxy-4-methylthiazole (14) upon heating with diluted hydrochloric acid. The thiazolic nature of oxymethylthiazole was clearly demonstrated by its reduction by zinc powder distillation into 4-methylthiazole (23), the first free thiazole ever described. 

Zwanenburg and Wynberg also proposed another route to the thienothiophene (112). 2,5-Dibromo-3,4-bisbromomethylthiophene (116) was cyclized with sodium sulfide to give 4,6-dibromo-l f,3/f-thieno[3,4-c]thiophene (117) in 60% yield 117 was then reduced to thienothiophene (112). l,3,7,9-Tetrabromo-4i/,67f,10.H, 12ff-dithieno-[3,4 C 3, 4 -/i][l,6]dithiecin (118) (18%) was also formed during the ring closure. Oxidation of thienothiophene (117) followed by reduction by zinc in acetic acid gave l/f,3H-thieno[3,4-c]thiophene 2,2-dioxide (119). ... 

Reduction by zinc in acetic acid of the trithiolane 171, derived from pinacolone by Gompper and Topfl, afforded 9% of 2,5-di-t-butyl-thieno[3,2-6] ophene (172) among other products [Eq. (49)]. 

This procedure is a modification of the method described for the preparation of 2-chlorophenylhydroquinone.s 2-/>-Acetyl-phenylquinone has been prepared by carrying out the coupling in alcohol solution in the presence of sodium acetate instead of sodium bicarbonate.2 Reduction by zinc, acetic acid, and a small amount of concentrated hydrochloric acid yielded 2- -ace-tylphenylhydroquinone.2... 

Reduction, by zinc and hydrochloric acid, of 5-anilino-3-hydroxy-1,2,4-thiadiazole causes the usual ring-opening at the S—N bond,... 

Reduction by zinc amalgam of a dry and oxygen-free THF solution containing [VC12(TPTP)] (TPTP = raeso-tetra-p-tolylporphyrinato) and addition of elemental sulfur yields [VS(TPTP)].659 Similar thiovanadyl complexes were prepared with OEP, TPP and TMTP (TMTP = meso-tetra-ra-tolylporphyrinato). Analytical results and mass spectra agree with the formulation [VS(por)], and v(V=S) was at 550-565 cm-1 (see Section 33.5.6.1). FT-EXAFS of [VO(OEP)] and [VS(OEP)] were recorded and the difference FT spectrum yielded... 

Zinc amalgam, or electrochemical reduction of porphyrinatoniobium(V) oxide acetates led to [NbIVOL] (L = OEP, TPP, TPTP).566 The [NbOLF]- anions have been obtained by controlled potential electrolysis of (i) the corresponding Nbv oxo acetate in the presence of PFg and (ii) the appropriate Mr oxo fluoride. Reduction by zinc amalgam of [M)LX3] (X = Q, Br) gave [NbtvLX2] 327 the ESR spectra of the six-coordinate complexes in frozen THF solution are consistent with trans coordination. 

Reduction by zinc dust yields an oil iodine in chloroform has no action, but chlorine in the same solvent gives selenium tetrachloride and chloroacetylacetone, and bromine yields lachrymatory products and a colourless crystalline substance of melting-point 180° C. Aqueous hydrogen sulphide causes slow decomposition, with liberation of sulphur and selenium. Potassium metabisulphite and sodium hydrogen sulphite transform selenium acetylacetone quantitatively into alkali selenodithionates, a reaction which affords the best known means of preparing these salts. 

Treatment of [RuCl(NH3)5]2+ with Ag+ followed by reduction by zinc amalgam in aqueous... 

Yur ev et al. 2 prepared deuteriated selenophenes from the respective halogenated compounds by halogen-deuterium replacement. Thus, 2-deuterio-, 2,5-dideuterio-, tetradeuterioselenophene, 3-methyl-, and 5-methyl-2-deuterioselenophene were obtained from the corresponding iodoselenophenes on reduction by zinc in deuteriated acetic acid. 3-Deuterioselenophene was obtained from 3-selenienyl-lithium hydrolyzed with deuteriated acetic acid at — 7 0°C the lithium derivative was obtained from 3-bromoselenophene and ethyllithium, also at — 70°C. The deuterium content was determined by combustion, the water being analyzed by the drop method.43... 

Three common procedures are available for the transformation of aldehydes and ketones to hydrocarbons (1) reduction by zinc and hydrochloric acid (Clemmensen), (2) reduction by hydrazine in the presence of a base (Wolff-Kishner), and (3) catalytic hydrogenation. In view of the complicated mixtures obtained by the polyalkylation of benzene by the Friedel-Crafts reaction (method 1), reduction of alkyl aryl ketones is the most reliable method for the preparation of di- and poly-alkylbenzenes. 

Protonation of the nitrogen is followed by reduction by zinc. This is a two-electron reduction, in which zinc is oxidized to Zn. The remainder of the mechanism involves acid-catalyzed reactions. 

Elphimoff-Felkin, I., Sarda, P. Reductions by zinc in the presence of acids. III. Reduction of alcohols, ethers, acetates, and allylic halides to olefins. Tetrahedron 1977, 33, 511-516. 

Stereoselective addition of t-BuBr to a, fi-enoates.2 Reaction of f-BuBr with diethyl mesaconate with reduction by zinc with ultrasound results in syn-1 and anti-1 in the ratio 85 15. Similar stereoselectivity obtains in radical reactions promoted... 

When deuterated compounds were being first prepared, the reduction of aliphatic halogen compounds to the corresponding deuterium compounds was effected mainly by potassium or aluminum amalgam in D20 the preparation of acetic acid from potassium trichloroacetate53 and of methane from bromoform54 may be cited as examples. Later, reduction by zinc in an acid medium was preferred 4d 5 5 for instance, thymine was labelled in the methyl group by reduction of (chloromethyl)uracil with zinc and deuterium chloride 24... 

Whereas mild reducing agents (sodium amalgam, zinc dust in hydrochloric acid) convert nitrosamines into A,A-disubstituted hydrazines, reduction by zinc and sulfuric acid or tin and hydrochloric acid cleaves with regeneration of the secondary amine.159 Nitrosamines are also cleaved smoothly by dilute sulfuric acid containing urea.160... 

The bromine in the above cyanamides is resistant to reduction by zinc and acetic acid. However, LXIII reverts to brucine (with the formation of silver bromide and silver cyanide) when it is heated in benzene with silver benzoate. 

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