Reduction Huang-Minlon

WOLFF - KISHNER HUANG MINLON Reduction Reduction ol ketones to hydrocarbons by heating with NHaNH2 and aqueous KOH (Wotff-Kishnei) or KOH in ethytene glycol (Huang-Minlon)... 

Cagniant and Cagniant have reported that succinoylation of benzo[6]thiophene under Friedel-Crafts conditions yields a separable mixture of the y-ketobutyric acids 42a and 43a in a ratio of 9 1 (combined yield 85%). Huang-Minlon reduction of 42a to the butyric acid (90%) followed by cyclization of the derived acid chloride (90%) was reported to yield 4-keto-l,2,3,4-tetrahydrodibenzothiophene (44a) (69% overall). Likewise, acylation of benzo[6]thiophene with the ester chloride of succinic acid in carbon disulfide-aluminum chloride gave a separable mixture (80%) of the 2- and 3-y-ketobutyric esters. Two alternative... 

Octahydrodibenzothiophene (73) has been prepared by the following sequence. Friedel-Crafts acylation of 4,5,6,7-tetra-hydrobenzo[6]thiophene with succinic anhydride (87%) or with the ester chloride of succinic acid followed by hydrolysis (80%), yields the keto acid (74). Huang-Minlon reduction of 74 followed by cyclization of the derived acid chloride with stannic chloride yields l-keto-1,2,3,4,6,7,-8,9-octahydrodibenzothiophene (53) (Section V,A). Reduction of 53 gives 73 as a solid (overall yield 32%). 

The Huang-Minlon reduction of 3-formylfuran surprisingly gave 3-methylene-2,3-dihydrofuran. The product undergoes ene reactions with a number of electron depleted alkenes and provides a route to functionalize the 3-position in furan as shown in Scheme 66 (93TL5221). 

Metal hydrides usually reduce the carbonyl to alcohol but LAH converts xanthone into a dixanthyl ether (454) or xanthene (453) according to the conditions. The latter product is also obtained by the Wolff-Kishner-Huang-Minlon reduction. Metal-liquid ammonia opens the pyran-4-one ring of chromones and flavones to form dihydrochalcones and other compounds (79JOC1494). 

Several pyridazines were prepared unintentionally by the attempted Wolff-Kishner reduction of ketoacids. It has been claimed that the ease of pyridazine formation during the Wolff-Kishner-Huang-Minlon reduction of aromatic 1,4-ketoacids depends on the nature of... 

WOLFF KISHNER HUANG MINLON Reduction Reduction of ketones to hydrocaitwns by heating with NH2NHa and aqueous KOH (Wolff-Kishnei) or KOH in ethylene glycol (Huang-Mmlon)... 

Huang-Minlon reduction of a similar compound, the method was inapplicable. So, we adopted the method of radical reduction of xanthate (+)-65 instead.42 Ketone (+)-63 was stereoselectively reduced with lithium tri-sec-butylborohydride (L-Selectride), yielding axial alcohol (+)-64 in 92% yield, which was then con-verted to xanthate (+)-65 in quantitative yield by treatment of lithium alkoxide of the alcohol with carbon disulfide and then with iodomethane. Xanthate (+)-65 was next reduced with tributyltin hydride, giving the desired methylene compound (+)-66 in 92% yield. After deprotection of the acetal group of (+)-66 (98% yield), ketone (+)-67 was converted to olefin (-)-68 in 98% yield by formation of tosyl-... 

Huang-Minlon reduction The modification of the Wolff-Kishner reaction in which the reaction is carried out in refluxing diethylene glycol. This version has completely replaced the original method. 

Hexyne, 159,231, 253 Homoconjugate addition, 219 Homogeranyl cyanide, 111, 112 Homologation, 272, 369 Horner-Wittig reaction, 61 Huang-Minlon reduction, 248 Hunsdiecker reaction, 279 Hunsdiecker-Cristol reaction, 323-324 Hydrazine, 26,248, 395 Hydrazine hydrate, 155, 336 Hydrazoic acid, 440... 

A modified Huang-Minlon reduction was found advantageous in the conversion of methyl eholate to lithocholic acid without purification of intermediates. The 3-hydroxyl group (equatorial) is selectively succinoylated, the hydroxyl functions... 

Badger and Buu-Hoi have made extensive use of nickel desulfurization in synthesis. One general scheme employs thiophene derivatives. For example 7-2-thienylbutyric acid (1, succinoylation of thiophene and reduction) is acetylated (as ester) at the 5-position (2) and converted by Huang-Minlon reduction and... 

Gardner and co-workers developed an efficient synthesis of pimelic acid (4) from furfural (1) involving conversion to furylacrylic acid (2) and esterification, which proceeds with cleavage of the ring and disproportionation to give diethyl y-ketopimelate (3). Huang-Minlon reduction by the usual procedure in diethylene... 

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