Sulfonylhydrazones

Salts of sulfonylhydrazones [R2C = NNS02Ar]- Photolysis or thermolysis diazoalkanes are intermediates R2C + N2 + ArS02 b... 

Carbenes from Sulfonylhydrazones. The second method listed in Scheme 10.8, thermal or photochemical decomposition of salts of arenesulfonylhy-drazones, is actually a variation of the diazoalkane method, since diazo compounds are intermediates. The conditions of the decomposition are usually such that the diazo compound reacts immediately on formation.147 The nature of the solvent plays an important role in the outcome of sulfonylhydrazone decompositions. In protic solvents, the diazoalkane can be diverted to a carbocation by protonation.148 Aprotic solvents favor decomposition via the carbene pathway. 

A disadvantage of this method of synthesis is that unless the conditions are carefully controlled, complete oxidation of the bis hydrazone occurs, the product being an acetylene. This problem can normally be avoided by using bis toluene-p-sulfonylhydrazones. These are... 

However, most frequently used methods for reduction of aromatic ketones to hydrocarbons are, as in the case of other ketones, Clemmensen reduction [160, 161, 758, 843, 844] Procedure 31, p. 213), Wolff-Kizhner reduction [280,281,282, 759, 774,845] Procedure 45, p. 216), or reduction of p-toluene-sulfonylhydrazones of the ketones with lithium aluminum hydride [811, 812] or with borane and benzoic acid [786]. 

Vilsmeier reaction, 49, 1 56, 2 Vinylcyclopropanes, rearrangement to cyclopentenes, 33, 2 Vinyllithiums, from sulfonylhydrazones, 39, 1... 

Another class of ballasted dye releasers is represented by the sulfonylhydrazone (88). These compounds interact with oxidized p-phenylenediamines to give sulfinate-solubilized dyes (89). Y can be the residue of an azo, anthraquinone or phthalocyanine dye (73BRP1321046, 75BRP1407362). 

The sulfonylhydrazone moiety in (77) is methylated at N-2 by iodomethane under basic conditions, and acetic anhydride gives the 2-acetyl derivative (68JHC453). The 1,2,4-thiadiazines (78 Y = leaving group) are acylated on N-4 by isocyanates. Reaction with a second molecule of isocyanate gives the bicyclic compounds (79) (74BSF1917). 

Support-bound sulfonylhydrazones can also be used as linkers for alkenes. Cleavage is effected by heating in the presence of an alcoholate, whereby diazoalkanes are initially formed these then undergo thermal fragmentation into the alkene and nitrogen (Entry 12, Table 3.43 Bamford-Stevens reaction). Polystyrene-bound alkynyl... 

Few preparations of nitriles have been performed on insoluble supports (Table 13.19). Aromatic and heteroaromatic nitriles have been prepared on solid phase from the corresponding iodoarenes by metallation followed by reaction with tosyl cyanide (Entry 1, Table 13.19). Moreover, the reaction of chloromethyl polystyrene with NaCN has been used to prepare support-bound benzyl cyanide (Entry 2, Table 13.19). Cleavage with simultaneous formation of nitriles can be achieved by treating polystyrene-bound sulfonylhydrazones with KCN (Entry 3, Table 13.19) or by cleaving amides from a Rink or Sieber linker with TFA anhydride (Entry 10, Table 3.38 [262]). Support-bound benzaldehydes have been converted into 3-aryl-2-propenenitriles by means of a Horner-Emmons reaction with (Et0)2P(0)CH2CN [263]. 

The reaction of Tentagel-bound carboxylic esters with amidooximes has been used to prepare oxadiazoles (Entry 11, Table 15.20). Thiadiazoles have been prepared from support-bound iV-sulfonylhydrazones by treatment with thionyl chloride. Thiadiazole formation and cleavage from the support occurred simultaneously (Entry 12, Table 15.20). Perhydro-l-thia-2,5-diazole-2,2-dioxides (sulfahydantoins) have been prepared by aminosulfonylation of amino acids esterified with Wang resin, followed by ring-closure with simultaneous cleavage from the support [257]. 

Chamberlin and coworkers38 showed that vinyllithium reagents derived from ketone (2,4,6-triiso-propylphenyl)sulfonylhydrazones undergo intramolecular carbolithiadon reactions with high dia-stereoselectivity (Scheme 13). 

A variation on the thermal reactions of diazo compounds with alkenes is the decomposition of salts of sulfonylhydrazones. This procedure, known as the BamfoTd-Stevens reaction, is believed to occur via the formation of diazo compounds. Subsequent 1,2-hydrogen shifts generally lead to the formation of alkenes as the final products. Cyclopropanes may also be formed as the result of intramolecular 1,3-C—H insertion reactions or when the original hydrazone substrate contains a remote alkenic group as a site for intramolecular cyclopropanation.10... 

Likewise, the sulfonylhydrazones 337a-c prepared from reactions of sodium benzenesulfinate with hydrazonoyl chlorides 20a-c in ethanol at room temperature cyclized in situ to give 338a, 338b, and 339, respectively (87MI1). 

Support-bound sulfonylhydrazones have been reduced to alkanes by sodium borohydride (Entry 5, Table 3). This reaction, which has not yet been fully optimized for solid-phase synthesis, should enable the support-aided conversion of ketones into alkanes under mild reaction conditions. 

The problem associated with radical cyclizations involving arene-sulfonylhydrazones as radical acceptors stemmed from the failure in harnessing the five- and six-membered ring radicals due to the fast hydrogen atom abstraction by the alkyl radicals as shown in Scheme 4. Thus, we thought that iV-aziridinylimines would be ideally suited for our purpose and thus studied radical cyclizations of 2-phenyl-/V-... 

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