Huang Minion

Method B (Huang - Minion modification of Wolff - Kishner reduction)... 

Huang Minion and Chung-Tungshun, Tetrahedron Letters, 1961, 666. 

This mixture is the Huang Minion modification of the Wolff Kishner reaction. In the editor s experience it often leaps from the flask with sudden gas evolution. In addition to the expected nitrogen, at the operating temperature of around 200°C it is uncomfortably near the temperature of hydrogen evolution from glycol decomposition. The reduction proceeds much cooler in dimethyl sulfoxide or some of the alkoxyethanols as solvent. 

The classical procedure for the Wolff-Kishner reduction—i.e. the decomposition of the hydrazone in an autoclave at 200 °C— has been replaced almost completely by the modified procedure after Huang-Minion The isolation of the intermediate is not necessary with this variant instead the aldehyde or ketone is heated with excess hydrazine hydrate in diethyleneglycol as solvent and in the presence of alkali hydroxide for several hours under reflux. A further improvement of the reaction conditions is the use of potassium tert-butoxide as base and dimethyl sulfoxide (DMSO) as solvent the reaction can then proceed already at room temperature. ... 

After preliminary technical improvements, Huang Minion (1946) introduced a modified procedure by which the reduction is conducted on a large scale at atmospheric pressure with efficiency and economy. The ketone is refluxed In a high-boiling watci-miscible solvent (usually di- or tricthy-lene glycol) with the aqueous hydrazine and sodium hydroxide to form the hydrazone water is then allowed to distil from the mixture till the temperature rises to a point favorable for decomposition of the hydrazone (200°) and the mixture is refluxed for three or four hours to complete the reduction. 

Friedel-Crafts acylation of benzo[6]thiophene and its derivatives with succinic anhydride132,439,662,663 or the ester chloride of succinic acid614, 618, 650,662 gives a y-keto acid (or ester), which is reduced to the corresponding y-(benzo[6]thienyl)butyric acid by the Huang Minion or Clemmensen method. y-(Benzo[6]thienyl)butyric acids may alternatively be prepared by the diethyl malonate synthesis on the appropriate halide,439,499 by the Arndt-Eistert reaction on the corresponding propionyl chloride,409,618 or by cyclization.347,618 The ketones (317 R = Hor OMe)347 have been prepared by cyclization... 

The first synthesis of the parent compound (1) was reported in i963,14 the best route starting from 2,3-dihydropyrrolizin-l-one (3a), which was transformed to the corresponding tosylhydrazone (182). Compound 1 was obtained from 182 in 29% yield, using Huang-Minion conditions. 

Biochemical studies conducted by Bush and coworkers [4,5] suggested that cortisol (hydrocortisone), the 1 1//-hydroxy analogue of cortisone, is the functional hormone and that cortisone owes its biological activity to enzymic conversion to cortisol in vivo. Therefore, the first chemical synthesis of cortisol was an important achievement This was accomplished by Wendler et al. [6] in 1950, and an improved synthesis was described by Wendler, Huang Minion, and Tishler [7] during the following year. 

The main use of hydrazine in steroid chemistry has been in the reduction of keto-groups to give unsubstituted methylene groups by the Wolff-Kishner process, particularly as modified by Huang-Minion fij. Hydrazones of simple ketones react rapidly at 200° in hydroxylic solvents such as "diethylene glycol containing strong alkali. 

The a -diketone (10) is reported to undergo Huang Minion reduction at an unusually low temperature (150 ) to give the... 

After preliminary technical improvements, Huang Minion (1946) introduced a modified procedure by which the reduction is conducted on a large scale at atmospheric pressure with efficiency and economy (L. M. Fieser). 

Reduction of ketones to hydrocarbons by heating with NH2NH2 and aqueous KOH (Wolff-Kishner) or KOH in ethylene glycol (Huang Minion) (see 1st edition). 

HOUBEN HOESCH Phenol acylation 162 Huang Minion 426 Hubert 232, 299... 

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