Sulfonyl hydrazones

C. Sulfonyl Hydrazones, Sulfonyl Hydrazides and Sulfonyl Azides... 

Removal of the carbonate ring from 7 (Scheme 1) and further functional group manipulations lead to allylic alcohol 8 which can be dissected, as shown, via a retro-Shapiro reaction to give vinyl-lithium 9 and aldehyde 10 as precursors. Vinyllithium 9 can be derived from sulfonyl hydrazone 11, which in turn can be traced back to unsaturated compounds 13 and 14 via a retro-Diels-Alder reaction. In keeping with the Diels-Alder theme, the cyclohexene aldehyde 10 can be traced to compounds 16 and 17 via sequential retrosynthetic manipulations which defined compounds 12 and 15 as possible key intermediates. In both Diels-Alder reactions, the regiochemical outcome is important, and special considerations had to be taken into account for the desired outcome to. prevail. These and other regio- and stereochemical issues will be discussed in more detail in the following section. 

Reduction, carboxyl groups, 56,83 Reduction of a,0-unsaturated p-toluene-sulfonyl-hydrazones to alkenes, 59,42 Reductive alkylation, 56,52 Reductive cleavage, 56, 101 Resolution of amines, 55,80, 83 Rexyn 201,55,4 Rhodium(III) oxide, 57, 1 Ring contraction, 56, 107 Ring expansion of cycloalkanones to cycloalkenones, 59, 113... 

Lissamine rhodamine B sulfonyl hydrazine can react with aldehyde groups to form hydrazone linkages. 

A parallel synthesis of 1,2,3-thiadiazoles employing a catch-and-release strategy has been reported using the Hurd-Mori reaction. A polymer-bound tosyl hydrazide resin reacted with a-methylene ketones to afford a range of sulfonyl hydrazones. Treatment of these sulfonyl hydrazones with thionyl chloride causes 1,2,3-thiadiazole formation and cleavage of the resin in one step <1999JOC1049>. 

A regiospecific solid-phase synthesis of 3-methylthiazolo[3,2-c][l,2,3]triazole 105 has been achieved using poly-styrene-sulfonyl hyrazide resin (PS-Ts-NHNH2) 287. The reaction of resin 287 with l-thiazol-2-yl-ethanone in 5% TiCU/MeOH provides hydrazone 288 and subsequent treatment of this latter compound with morpholine at 95 °C gave fused triazole 105 in 60% yield (Scheme 29) <2004TL6129>. 

Kinetics and mechanisms of gas-phase pyrolysis of sulfonyl hydrazones and their oxime analogues have been reported for the first time " it is proposed that cyanoarene formation arises in each case via a six-membered transition state (60). The lower limit... 

Fragmentation of a,P-epoxyketones via the intermediacy of a,P-epoxy sulfonyl-hydrazones. 

Numerous methods to prepare individual classes of aliphatic diazo compounds have been extensively developed. The major strategies for their synthesis involve the alkaline cleavage of N-alkyl-N-nitroso-ureas, -carboxamides and -sulfonamides, dehydrogenation of hydrazones, as well as diazo group transfer from sulfonyl and related azides to active methylene compounds, and electrophilic diazoalkane substitution reactions. These synthetic methods have been comprehensively reviewed (15,16). Useful information on the preparation of selected diazo compounds can be found elsewhere (6,17). 

The yields of pyridines are generally low, but precursors for equation (10) are easily prepared by condensation of cinnamaldehydes with acetophenones. Sulfonyl- and acyl-hydrazones of o-ethynylbenzaldehyde can be cyclized by base to give isoquinolinium ylides (equation 12) (80JCS(P1)1331>. 

Toluene p-sulfonyl hydrazones (tosyl hydrazones) undergo C=N oxidative bond cleavage with H202 in the presence of TS-1, to give high yields of the corresponding carbonyl compounds very likely, the reaction proceeds through... 

Lissamine rhodamine B sulfonyl hydrazine is a hydrazide derivative of sulforhodamine B that can spontaneously react with aldehyde- or ketone-containing molecules to form a covalent, hydrazone linkage (Fig. 217). It also can be used to label cytosine residues in DNA or RNA by use of the bisulfite activation procedure (Chapter 17, Section 2.1). The resulting fluorescent derivative exhibits an excitation maximum at a wavelength of 556 nm and a maximal emission wavelength of 580 nm when dissolved in methanol. In... 

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