Sulfonate esters, reactions

Alcohols are frequently more readily available than the corresponding alkyl hahdes, and the development of the sulfonate ester reaction by... 

Azide is a potent nucleophile and can react with electrophilic substrates other than halides and sulfonate esters. Reaction of azide with the epoxide moiety in carboethoxy oxirane (ethyl glycidate) was followed by catalytic hydrogenation of the azide and hydrolysis of the ester to give isoserine (3-amino-2-hydroxypropanoic acid, 1.23). This synthetic approach to isoserine dates to 1879. 3... 

Very few 4-aminothiazoles have been synthetized directly. The reaction of a-halonitriles with thioamides generally fails and only extensive decomposition results. However, the benzene sulfonic ester of mandelonit-rile reacts with thiobenzamide to give 2,5-diphenyl-4-aminothiazole (257), Ri = R2 = Ph, in 37% yield (Scheme 132) (417) Similarly, a-cyano-a-acetylthioacetamide condensed with a-chloroacetonitrile give 257, Ri = CH(CN)CH3 and R2 = H (804). 

Sulfonate esters are subject to the same limitations as alkyl halides Competition from elimination needs to be considered when planning a functional group transforma tion that requires an anionic nucleophile because tosylates undergo elimination reactions just as alkyl halides do... 

The reaction of alcohols with acyl chlorides is analogous to their reaction with p toluenesulfonyl chloride described earlier (Section 8 14 and Table 15 2) In those reactions a p toluene sulfonate ester was formed by displacement of chloride from the sulfonyl group by the oxygen of the alcohol Carboxylic esters arise by displacement of chlonde from a carbonyl group by the alcohol oxygen... 

Photoresist appHcations in the microelectronics industry have also been disclosed (340). Thermally stable ben2yl sulfonate esters based on 2-methyl-3-nitroben2otrifluoride [6656-49-1] can serve as nonionic photoacid generators to promote a cascade of reactions during irradiation of the resist. 

PyrogaUol has been cited for use in photosensitive compositions. It is used in the form of sulfonate esters of quinonediazides which hydrolyze when exposed to actinic light to Hberate the acid which, in turn, catalyzes further reaction of novolak resins (60). 

Sulfonate Esters. Sucrose sulfonates are valuable intermediates for the synthesis of epoxides and derivatives containing halogens, nitrogen, and sulfur. In addition, the sulfonation reaction has been used to determine the relative reactivity of the hydroxyl groups in sucrose. The general order of reactivity in sucrose toward the esterification reaction is OH-6 OH-6 > OH-1 > HO-2. 

An aiyl methane- or toluenesulfonate ester is stable to reduction with lithium aluminum hydride, to the acidic conditions used for nitration of an aromatic ring (HNO3/HOAC), and to the high temperatures (200-250°) of an Ullman reaction. Aiyl sulfonate esters, formed by reaction of a phenol with a sulfonyl chloride in pyridine or aqueous sodium hydroxide, are cleaved by warming in aqueous sodium hydroxide. ... 

Sulfonate esters are especially useful substrates in nucleophilic substitution reactions used in synthesis. They have a high level of reactivity, and, unlike alkyl halides, they can be prepared from alcohols by reactions that do not directly involve bonds to the carbon atom imdeigoing substitution. The latter aspect is particularly important in cases in which the stereochemical and structural integrity of the reactant must be maintained. Sulfonate esters are usually prepared by reaction of an alcohol with a sulfonyl halide in the presence of pyridine ... 

The most common leaving groups are sulfonate esters and halides. For the sake of convenience, the discussion of certain dehalogenation reactions is also included in this section even though they may not involve 8 2 type displacement. Benzylic alcohols are also known to be displaced by hydrides or deuterides, but there is no evidence for the application of these reactions to the steroid field. 

Only one of these methods, namely the reaction of halides with lithium aluminum deuteride, is a true displacement reaction, following the same course as the previously discussed displacement of sulfonate esters (section Vl-A). Thus, lithium aluminum deuteride treatment of 7a- and 7jS-bromo-3 -benzoyloxy-5a-cholestanes (195) and (196) gives the corresponding deuterium labeled cholestanols (197) and (198) respectively." ... 

The most satisfactory method of dehydrating 12a-alcohols appears to be through the sulfonate esters Engel and coworkers have shown (ref. 236 and ref. cited therein) that treatment of such sulfonates with alumina gives A -compounds. The reaction appears to be subject to steric acceleration in that bulky IToc-substituents and cw-fused A-rings aid elimination, and that yields increase with increasing size of the sulfonate employed. 

Reaction of Halides and Sulfonate Esters with Meta ... 

An example of cleavage ol the sulfur-oxygen bond in trifluoromethane-sulfonic ester has been reported Tnfluororaethyl triflate reacts with neutral or anionic nucleophiles with elimination of carbonyl difluoride and formation of trifluoromethanesulfonyl fluoride [57] (equation 32) The mechanism of this reaction involves elimination of fluoride ion, which is a chain carrier in the substitution of fluorine for the trifluoromethoxy group... 

Reactions of Organic Fluorine Compounds Table 13. Reactions of Sulfonate Esters with Nucleophiles... 

The mechanisms by which sulfonate esters undergo nucleophilic substitution are the sfflne as those of alkyl halides. Inversion of configuration is observed in Sn2 reactions of alkyl sulfonates and predominant inversion accompanied by racernization in SnI processes. 

Conversion to p-toluenesulfonate esters (Section 8.14) Alcohols react with p-toluenesulfonyl chloride to give p-toluenesulfonate esters. Sulfonate esters are reactive substrates for nucleophilic substitution and elimination reactions. The p-toluenesulfonate group is often abbreviated —OTs. 

Another deviation from the normal displacement reaction of primary tosylates occurs in nucleoside derivatives (39, 81) where cyclonucleosides and anhydronucleosides are formed by participation of a nitrogen atom (as in purine nucleosides) and oxygen atom (as in pyrimidine nucleosides ), respectively. Iodonucleosides can result from these reactions only if these cyclic compounds are prone to attack by iodide ion. Several new examples of unexpected reactions during the solvolysis of sulfonate esters in sugar derivatives have been recorded in the past few years (2, 4,5,7,15,44,62,63,94). 

Metal halide salts other than sodium iodide have been used sparsely to prepare halodeoxy sugars from sulfonate esters. Lithium chloride (107) and lithium bromide (33) have found limited application. Potassium fluoride (dihydrate) in absolute methanol has been used (51, 52) to introduce fluorine atoms in terminal positions of various D-glucose derivatives. The reaction is conducted in sealed tube systems and requires... 

The use of tetra-n-butylammonium fluoride (54) in an aprotic solvent such as acetonitrile may be more advantageous. Foster and colleagues (19, 37) have effected an SN2 type of reaction using this reagent in the conversion of l,2 5,6-di-0-isopropylidene-3-0-p-tolylsulfonyl-D-allofura-nose into the C-3 epimeric fluorodeoxy derivative. Note that whereas potassium fluoride is ineffective in displacing secondary sulfonate esters in sugars, tetra-n-butylammonium fluoride is capable of effecting a displacement with Walden inversion even in a furanose drivative. 

The direct reaction of 1-alkenes with strong sulfonating agents leads to surface-active anionic mixtures containing both alkenesulfonates and hydroxyalkane sulfonates as major products, together with small amounts of disulfonate components, unreacted material, and miscellaneous minor products (alkanes, branched or internal alkenes, secondary alcohols, sulfonate esters, and sultones). Collectively this final process mixture is called a-olefinsulfonate (AOS). The relative proportions of these components are known to be an important determinant of the physical and chemical properties of the surfactant [2]. 

Neutral oil consists of unreacted alkenes, alkanes, secondary alcohol byproducts, sulfonate esters, and sultones. Calculation of the concentration of neutral oil present in AOS, taken together with separate determinations for alkenes and alcohols (see below) and nonvolatile material (determined by residue on evaporation), can be used as a measure of the completeness of the sulfona-tion reaction. 

FIG. 29 Neutral sulfonate ester components in the acid reaction mixture. 

Only the a-olefins are sulfonated commercially to make a-olefinsulfonate (AOS). The chemistry of a-olefin sulfonation is usually described in terms of three stages. The initial sulfonation reaction involves the formation of 3-sul-tones. This initial step is so fast as to be almost instant. Reaction of the initially formed B-sultones with more S03 is competitive with sulfonation of the olefin. This side reaction produces a byproduct believed to be a cyclic pyro-sulfonate ester, i.e., a pyrosultone ... 

The Reaction of Alkyl Halides and Sulfonate Esters With Group I (I A) and II (II A) Organometallic Reagents ... 

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