Sulfur compounds lithium aluminum hydride

Lithium aluminum hydride reduces most sulfur compounds with cleavage of the C—S bond, including thiols. " Thioesters can be reduced with Ni2B (from NiBr2/... 

The stoichiometry of lithium aluminum hydride reductions with other compounds such as nitriles, epoxides, sulfur- and nitrogen-containing com-... 

Phthalimide was hydrogenated catalytically at 60-80° over palladium on barium sulfate in acetic acid containing an equimolar quantity of sulfuric or perchloric acid to phthalimidine [7729]. The same compound was produced in 76-80% yield by hydrogenation over nickel at 200° and 200-250 atm [43 and in 75% yield over copper chromite at 250° and 190 atm [7730]. Reduction with lithium aluminum hydride, on the other hand, reduced both carbonyls and gave isoindoline (yield 5%) [7730], also obtained by electroreduction on a lead cathode in sulfuric acid (yield 72%) [7730]. 

Amides containing nitro groups are reduced to diamino compounds with alane. A, A -Dimethyl-p-nitrobenzamide, on reduction with lithium aluminum hydride in the presence of sulfuric acid in tetrahydrofuran, gave 98% yield of dimethyl-p-aminobenzylamine [1117]. 

A sulfuric acid solution of the oxide (25-75% solution) can be reduced with tin, copper, zinc, and other reducing agents forming a blue solution of molybdenum blue which are hydrous oxides of non-stoichiometric compositions (see Molybdenum Blue). Reduction with atomic hydrogen under carefully controlled conditions yields colloidal dispersion of compounds that have probable compositions Mo204(OH)2 and Mo40io(OH)2. Reduction with lithium aluminum hydride yields a red compound of probable composition MosOtIOEOs. Molybdenum(Vl) oxide suspension in water also can be reduced to molybdenum blue by hydriodic acid, hydrazine, sulfur dioxide, and other reductants. 

Challenger and Harrison found both thienothiophene 1 and its isomer 2 in the products of the reaction between acetylene and sulfur. To identify these compounds, Challenger et developed syntheses of unsubstituted and 2-alkyl-substituted thieno[3,2-f>]thiophene (2) from thiophene derivatives. Cyclization of (3-thienylthio)acetic acid in the presence of sulfuric acid gave 2,3-dihydrothieno[3,2-6]thiophen-3-one (22) (R = H) in 14% yield reducing the latter with lithium aluminum hydride resulted in thienothiophene (2) formation in 80% yield [Eq. (9)]. Similarly 2-methyl- and 2-ethyl-2,3-dihydrothieno[3,2-/>]thiophen-3-one were obtained from a-(3-thienylthio)propionic and a-(3-tWenylthio)-butyric acids in 30% and 27% yields, respectively their reduction yielded 2-methyl (32%) and 2-ethylthieno[3,2-6]thiophenes (52%). The parent acids were prepared from 3-mercaptothiophene. ... 

DL-Dihydrostreptose and its ribo isomer were similarly obtained. Birch reduction of 2-methyl-3-furoic acid, followed by addition of methanol, bromination, and dehydrobromination, gave 402 as a mixture of the isomers. Hydroxylation of 402 with osmium tetraoxide-so-dium chlorate, and subsequent treatment with acetone-sulfuric acid afforded three isomeric acetals (403-405). The structures of these compounds were assigned on the basis of their H-n.m.r. spectra. In addition, the relationship between 403 and 404 was established by hydrolysis and reglycosidation. The methyl esters 403-405 were quantitatively reduced to the corresponding alcohols. The mixture of alcohols obtained from 403 and 404 was converted into crystalline 5-deoxy-3-C-(hydroxymethyl)-l,2-0-isopropylidene-a-DL-ribofuran-ose (406), which was compared directly with a sample prepared from D-xylose. Methyl 5-deox y-3-C-(hydroxy methyl)-2,3-O-isopropy lidene-/3-DL-lyxofuranoside (407), obtained by reduction of 405 with lithium aluminum hydride, was hydrolyzed with dilute hydrochloric acid, to give a,/3-DL-dihydrostreptose.2,ifi... 

While aromatic nitro and azoxy compounds have been reduced to azo compounds with lithium aluminum hydride, aliphatic nitro compounds produced only the corresponding aliphatic amines [65]. The usual technique involves dropwise addition of 1 mole of nitro compound in ether to 1.05-1.15 moles of lithium aluminum hydride in ether solution at Dry Ice temperatures followed by warming to room temperature. If the resulting product is only slightly soluble in ether, hydrolysis should be carried out with dilute sulfuric acid. Then the azo compound simply needs to be filtered off, washed with water, and dried. If the product is ether-soluble, the ether layer is separated, evaporated, and the residue is recrystallized [65, 66]. 

In some runs, small amounts of sulfur-containing compounds distilled together with the amide. These impurities did not affect the yield and purity of the N,N-dimethylcyclohexylmethylamine obtained in the subsequent reduction with lithium aluminum hydride. 

The reactions of 1-TMS-cyclohexene oxide are similar (112). Treatment78,82 with sulfuric acid/water (in acetone), concentrated hydrobromic acid, sulfuric acid/ methanol, lithium aluminum hydride afford the corresponding compounds 1,2-di-hydroxy- (113)-, l-bromo-2-hydroxy- (114)-, l-methoxy-2-hydroxy- (115)-, 1-hydroxy-2-TMS-cyclohexane (117). Application of base to 115 yields 1-methoxy-l-cyclohexene (116). Pyrolysis of 112 gives a mixture of 1-trimethylsiloxy-l-cyclo-hexene (118) and 3-trimethylsiloxy-1-cyclohexene (ii9)77 (Scheme 13). 

The mesoionic compound (87) undergoes nucleophilic attack by aniline at C-2 to yield (88), which further reacts with excess aniline to give (89) and (90). Lithium aluminum hydride reduction of (87) removes the sulfur atom to give (91 Scheme 9) (70SST( 1)449, p. 452). 

One Te-C bond in a diorgano tellurium can be cleaved by alkali metals, organic lithium compounds, sodium hydroxide, lithium aluminum hydride, sodium borohydride, Grignard reagents, tributyltin hydride, sulfuric acid, sodium sulfide, sulfuryl chloride, hydrogen bromide, bromine, or iodine. The Te-C bond can also be broken thermally or through photostimulation. 

The addition of nitrosyl chloride to cyclohexene in sulfur dioxide at low temperature21 -25, or the reaction of cyclohexene with 3-methylbutyl nitrite and hydrochloric acid (producing nitrosyl chloride in situ)25 gave only the tram-adduct 1, isolated in high yield as a crystalline nitroso dimer (azodioxy compound) with E configuration at the N—N double bond. The trans configuration of the chloro and nitroso groups (mixture of diaxial and diequatorial conform-ers) was deduced by IR and H-NMR analyses (a mixture of conformers with both axial and both equatorial substituents is apparent)23-25 and by reduction with lithium aluminum hydride in tetrahydrofuran to yield tram-2-chloro-l-cyclohexanamine (trans-2)23. 

Ring opening of 5,6-dideoxy-5,6-epithio-l,2-0-isopropylidene-/3-L-idofiiranose with potassium methylxanthate leads to 1,2-O-isopropyl-idene-5,6-dithio-5,6-S-thiocarbonyl-/3-L-idofuranose, which can be reductively cleaved with lithium aluminum hydride to 1,2-O-isopro-pylidene-5,6-dithio-)3-L-idofuranose. Acid hydrolysis of the latter compound would be expected to give a 1,6-anhydroidose derivative having a sulfur atom in both the pyranose ring and the anhydro ring, but a definitive product was not isolable. 

The reduction of secondary sulfonates with lithium aluminum hydride or sodium borohydride is usually a poor reaction for deoxygenating secondary alcohols [220,222], In most cases, the hydride attack will occur at sulfur and result in cleavage of the S-0 bond to afford the starting secondary alcohol as the main product. An exception from this rule is observed when tetrabutylammonium borohydride is used for reduction of secondary triflates in refluxing benzene [239]. Under these conditions clean displacement with hydride occurs to give the corresponding deoxy compounds in good yield (O Table 14). 

Reductive 1,2-eIimination of chlorine and bromine from adducts of l-bromo-2-chlorocyclo-propene (see Section 5.2.2.1.2.5.) with oxygen and sulfur hetarenes has served in the synthesis of a number of cycloproparenes. This transformation is effected by low-valent titanium together with lithium aluminum hydride or an organolithium compound. Thus, reaction of the adduct 3 of l-bromo-2-chlorocyclopropene and 1,3-diphenylisobenzofuran with tita-nium(III) chloride and lithium aluminum hydride overnight in tetrahydrofuran led to elimination of both halogens together with extrusion of the oxygen and formation of 2,7-diphenyl-l/f-cyclopropa[ ]naphthalene (4) in 72% yield. 

The cis relationship between the phenyl and methoxyl groups in CLIX has been confirmed by recent synthetic studies of Uyeo and his co-workers (86). Dihydroisotazettinol (in which the 3-hydroxyl and the phenyl are trans) was oxidized by manganese dioxide to CLIXa. Treatment of CLIXa with lithium aluminum hydride and cyclization of the resultant triol with dilute sulfuric acid gave an ether (CLIXb), the methi-odide of which afforded the neutral compound CLIXc upon Emde reduction. The synthesis of CLIXc started with CLIXd, the condensation product of piperonyl cyanide and methyl acrylate. Dieckmann... 

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