Tosylhydrazones.

Tosylhydrazones.—The reaction between suitable tosylhydrazones and alkyl-lithium was reported in 1967 to afford high yields of olefins, the less-substituted olefin being favoured where two possibilities exist (Hoffman-type products). In the reviewer s own experience, and that of other workers,this reaction can be unreliable, giving complex mixtures of products, some containing nitrogen. More recently, it was reported that the reaction succeeds when a limited amount of methyl-lithium in hexane is added dropwise to the steroid tosylhydrazone in tetrahydrofuran, under nitrogen e.g. 2-ene, 3-ene, 6-ene, and 1,3-diene, from 

Hayashi and T. Komeno, Chem. and Pharm. Bull. (Japan), 1969, 17, 2319. 

Tosylazo-enes (e.g. 435), derived from the a-halogeno-ketones, undergo alcoholysis to give enol ethers (436), probably via addition-elimination as illustrated. In the case of 21-substituted pregnan-20-ones (437 X = F or OMs), 

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Shapiro and Related Reactions Organic Reactions 1990, 39, 1 1976, 23, 405 - Reaction of a tosylhydrazone with a strong base to give an olefin. 

Bam ford-Stevens Reaction- initial conversion of a tosylhydrazone to a diazo intermediate... 

A few special syntheses of thiirane derivatives from four-membered sulfur heterocycles are known. Methylenethiiranes are derived by thermolysis of the tosylhydrazones of thietan-3-ones (Scheme 143) (81TL4815), and 2,2,3,3-tetrakis(trifluoromethyl)thiirane is obtained by thermolysis of 2,2,4,4-tetrakis(trifluoromethyl)-l,3-dithietane 1,1-dioxide with loss of sulfur dioxide. 2,2,3,3-Tetrakis(trifluoromethyl)thiirane 1,1-dioxide is obtained in low yield by heating a mixture of 3,3-bis(trifluoromethyl)-l,2,4-oxadithietane 2,2,4,4-tetroxide and bis(trifluoromethyl)ketene. The mono-episulfide of norbornadiene is obtained from thietane derivative (65 Scheme 144) (73JOC649). 

E)-Spiro[12,ll]letracos-13-ene (2).3 Spiro tosylhydrazone 1 (0 275 g, 0 53 mmol) in diglyme (8 mL) under N2 was treated with MeONa (0 11 g. 2 mmol) Afterl h rellux the mixture was extracted with Et20. the extract washed (brine) and evaporated to afford 0 t6 g ol 2 (91%), mp 64 se C (pentane)... 

Two techniques, electrochemical reduction (section IIl-C) and Clem-mensen reduction (section ITI-D), have previously been recommended for the direct reduction of isolated ketones to hydrocarbons. Since the applicability of these methods is limited to compounds which can withstand strongly acidic reaction conditions or to cases where isotope scrambling is not a problem, it is desirable to provide milder alternative procedures. Two of the methods discussed in this section, desulfurization of mercaptal derivatives with deuterated Raney nickel (section IV-A) and metal deuteride reduction of tosylhydrazone derivatives (section IV-B), permit the replacement of a carbonyl oxygen by deuterium under neutral or alkaline conditions. 

Reduction of tosylhydrazone derivatives to the corresponding methylene analogs with metal hydride complexes provides an excellent solution to this problem. Soon after the discovery of this reaction it was recognized... 

The extent of olefin formation depends on the position of the functional group, " on the degree of a-substitution and on the concentration of the hydride (or deuteride). Usually olefin formation can be largely suppressed by increasing the concentration of lithium aluminum deuteride. With certain tosylhydrazones, however, such as the C-17 derivative (103), olefin (104) is a major product irrespective of the quantity of the reagent used. ... 

Thus, the reduction of tosylhydrazones with sodium borodeuteride in dioxane provides only monodeuterated analogs. For the insertion of two deuteriums it is necessary to first exchange the hydrazone proton and to carry out the reduction in aprotic or deuterated solvents. Under these conditions the reduction of the tosylhydrazone derivatives of 7- and 20-keto... 

Deuteration at C-3 by Lithium Aluminum Deuteride Reduction of 5a.-Pregnane-3,20-dione 3-Tosylhydrazone 20-Ethylene keta ... 

Reduction of Steroidal Tosylhydrazones with Sodium B orodeuteride... 

The following general procedure has been used for the reduction of the tosylhydrazone derivatives of various steroidal ketones. A mixture of the tosylhydrazone (50 mg) and sodium borodeuteride (50 mg) in dry dioxane (3 ml) is heated under reflux for 2 hr, and then the excess deuteride is decomposed by the addition of a few drops of acetic acid. Ether is added and the resulting solution is washed with 2 N sodium bicarbonate solution and... 

The reduction of a,jS-unsaturated ketones to olefins may also be effected via the tosylhydrazones (see section XI-A). 

The Bamford-Stevens decomposition of tosylhydrazones by base has been applied to steroids, although not extensively. It has been demonstrated that the reaction proceeds via a diazo compound which undergoes rapid decomposition. The course of this decomposition depends upon the conditions in proton-donating solvents the reaction has the characteristics of a process involving carbonium ions, and olefins are formed, often accompanied by Wagner-Meerwein-type rearrangement. In aprotic solvents the diazo compound appears to give carbene intermediates which form olefins and insertion products ... 

The reaction is not usually very satisfactory, although favorable results have been reported on occasion. Tosylhydrazones of 7-ketones give A -olefins ... 

The reduction of tosylhydrazones by complex metal hydrides has been used very effectively to prepare saturated steroid hydrocarbons in high yields. ... 

The alkyl lithium method gives high yields of -olefins from 17-ketones via the tosylhydrazones. A -Olefins are formed from 6- and 7-ketones. (Compare with the Bamford-Stevens reaction which gives A - and A -olefins, respectively.) In the presence of an excess of alkyl lithium, alkylation may occur. 

Deuteration at C-3 by lithium aluminum deuteride reduction of 5a-pregnane-3, 20-dione 3-tosylhydrazone 20-ethylene ketal, 177... 

Olefin formation by reduction of keto derivatives via tosylhydrazones, 354 Olefin formation by reduction of thioketals, 356... 

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