Kishner s. Wolff

Kiliani reagent 16, 138 Kindler s. Willgerodt King reaction 16, 777 Kishner s. Wolff Knoevenagel condensation 7, 781... 

Hooz reaction of boranes with diazo compds. 24,817 Huang Minion rednctimi s. Wolff-Kishner Hiinig base s. Ethyl-diisopropylamine Hydantoin ring,... 

J,19-cyclosteroids 19, 814 Horner synthesis 14, 877 Huang Minion reduction s. Wolff-Kishner Hydantoin dyes 19, 309 Hydantoins... 

Low-valent nitrogen and phosphorus compounds are used to remove hetero atoms from organic compounds. Important examples are the Wolff-Kishner type reduction of ketones to hydrocarbons (R.L. Augustine, 1968 D. Todd, 1948 R.O. Hutchins, 1973B) and Barton s olefin synthesis (p. 35) both using hydrazine derivatives. 

Die Reduktion von Tosyl-hydrazonen mit Hydriden zu Kohlenwasserstoffen stellt eine praparativ vorteilhafte Variante der Wolff-Kishner-Reduktion dar. Diese Methode ermoglicht durch geeignete Wahl des Reduktionsmittels die selektive Reduktion von p-Tosyl-hydrazonen unter Erhalt von Alkoxycarbonyl-, Aminocarbonyl-, Cyan- und Ni-tro-Gruppen. Zur Reaktion ist manchmal auch ein Gemisch der Oxo-Verbindung mit To-syl-hydrazin6 anwendbar. Die Reaktion verlauft ahnlich wie bei den Diazonium-Salzen (s. S. 484) iiber das entsprechende Diazen7 8 ... 

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. 

Propanes in the Wolff-Kishner Reduction of a,/S-unsaturated Carbonyl Compounds. J. chem. Soc. [London] 1952, 4686. 

Ganter has developed three different approaches to tricyclo[5.2.1.0 ]decane (403), yet another of the nineteen isomeric hydrocarbons of adamantaneland As seen in Scheme XXXIII, the routes involve intramolecular cyclization of keto tosylate 399 followed by Wolff-Kishner reduction of the resulting ketone, thermo-cyclization of 400 and subsequent dechlorination, hydrogenation, and photocycli-zation of aldehydes 401. Majerski s approach involved hypoiodite cleavage of alcohol 402... 

A common alternative to the Wolff-Kishner reduction of cyclobutanones to the parent cyclobutane (see Section S.2.4.2.), is formation of thiocetals (see Section 5.2.4.7.1.) followed by hydrogenolyses using Raney nickel.64,146-149 For example, l,4,4-trimethyl-6,6-(propane-l,3-diyldithia)bicyclo[3.2.0]heptan-3-one gave 15 using this method. It was found that the W-2 quality of Raney nickel works well.64"148... 

Both chemical and catalytic methods are available to convert chromanones to chromans, and flavones to flavans. Clemmensen s method is the most commonly used and usually gives good yields, but diborane is sometimes preferable. The Wolff-Kishner method appears to degrade the pyran ring and is rarely used on chromanones. The conditions of catalytic reduction have to be rather more drastic in order to produce chromans and flavans but much depends on the activity of the catalyst and on the solvent used. If the chromanol is first formed, more severe conditions are usually required to complete the reduction (77HC(31)207>. 

The first microwave-assisted Wolff-Kishner reduction was described by Parquet and Lin in 199763. The transformation of isatin to oxindole was performed on a small scale in a domestic microwave oven in two steps with a total reaction time of 40 s, as compared to 3—4 h if classical heating was utilised (Scheme 4.36). The first step involved the transformation of the carbonyl group into the hydrazone with 55% hydrazine in ethylene glycol and medium power microwave irradiation for 30 s. In the subsequent reduction step, KOH in ethylene glycol was used to substitute the more hazardous sodium ethoxide. The reaction mixture was irradiated for 10 s and the product was obtained in a yield of 32%. 

Gadhwal, S., Baruah, M. and Sandhu, J.S., Microwave induced synthesis of hydrazones and Wolff-Kishner reduction of carbonyl compounds, Synlett, 1999, 1573-1574. 

Chattopadhyay, S., Banerjee, S.K. and Mitra, A.K., The Huang-Minlon modification of Wolff-Kishner reduction in rapid and simple way using microwave technology, /. Indian Chem. Soc., 2002, 79,906-907. 

The Wolff-Kishner Reduction does nothing more than reduce a Ketone or aldehyde by removing the oxygen and replacing h with two hydrogens. You can do the same thing by adding hot acid to a ketone or aldehyde, but some ketones and aldehydes can t survive the hot acid. That s where the Wolff-Kishner Reduction comes in. 

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