Halogenated sulfines

Similar halogenations have been done on 2-lithio-l-phenylsulfonylindole[2], 2-Lithio-l-phenylsulfonylindole is readily converted to the 2-(trimethylsilyl) derivative[2,3]. 2-Trialkylstannylindoles can also be prepared via 2-lithio-indoles[4,5], 2-Sulfonamido groups can be introduced by reaction of a 2-lithioindole with sulfur dioxide, followed by conversion of the sulfinic acid group to the sulfonyl chloride with A-chlorosuccinimide[6]. 

Other interactions of /3-lactams with electrophiles include the oxidative decarboxylation of the azetidin-2-one-4-carboxylic acid (85) on treatment with LTA and pyridine (81M867), and the reaction of the azetidin-2-one-4-sulfinic acid (86) with positive halogen reagents. This affords a mixture of cis- and trans-4-halogeno-/3-lactams (87), the latter undergoing cyclization to give the bicyclic /3-lactam (88) (8UOC3568). 

Nucleophilic substitutions of halogen by the addition-elimination pathway in electron-deficient six-membered hetarenes by sulfinate anions under formation of sulfones have been described earlier120. The corresponding electron-poor arenes behave similarly121 (equation 30). A special type of this reaction represents the inverse Smiles rearrangement in equation 31122. 

Some particular features should be mentioned. Instead of Michael additions, a-nitroolefins are reported to yield allyl sulfones under Pd catalysis (equation 21). Halogenated acceptor-olefins can substitute halogen P to the acceptor by ipso-substitution with sulfinate (equation 22 , equation 23 ) or can lose halogen a to the acceptor in the course of a secondary elimination occurring P to the introduced sulfonyl groups (equation 24). On the other hand, the use of hydrated sodium sulfinates can lead to cleavage at the C=C double bond (equation 25). 

Sulfur dioxide (see above) as well as S02, SO , and SOj have been used as building blocks in three-component sulfone syntheses. It has long been known that aromatic sulfinic acids are easily available from diazonium salts and sulfur dioxide under copper catalysis . Mechanistically, aryl radicals as reactive intermediates add to sulfur dioxide generating arenesulfonyl radicals, which either take up an electron (or hydrogen) yielding a sulfinic acid or add to an olefinic double bond yielding final y -halogenated alkyl aryl sulfones (equation 78). 

Types of compounds are arranged according to the following system hydrocarbons and basic heterocycles hydroxy compounds and their ethers mercapto compounds, sulfides, disulfides, sulfoxides and sulfones, sulfenic, sulfinic and sulfonic acids and their derivatives amines, hydroxylamines, hydrazines, hydrazo and azo compounds carbonyl compounds and their functional derivatives carboxylic acids and their functional derivatives and organometallics. In each chapter, halogen, nitroso, nitro, diazo and azido compounds follow the parent compounds as their substitution derivatives. More detail is indicated in the table of contents. In polyfunctional derivatives reduction of a particular function is mentioned in the place of the highest functionality. Reduction of acrylic acid, for example, is described in the chapter on acids rather than functionalized ethylene, and reduction of ethyl acetoacetate is discussed in the chapter on esters rather than in the chapter on ketones. 

Chlorine, Antimony trichloride, Tetramethylsilane, 4047 Chlorine, 2-Chloroalkyl aryl sulfides, Lithium perchlorate, 4047 Sulfin tetrafiuoride, 2-(Hydroxymethyl)furan, Triethylamine, 4350 Titaniiun, Halogens, 4919... 

Miscellaneous Preparations of Acetylenic Deri vatives 1. Halogen Compounds, Sulfinates, Sulfonates and Acetates All temperatures are internal, unless indicated otherwise... 

Alkylation of Sulfinic Acid Salts Alkylsulfonyl-de-halogenation... 

The nucleophilic displacement of halogens by pentafluorophenoxide ion resulted in the formation of the corresponding esters [31] (equadon 29) (Table 12). Reactions of trifluaromethanesulfinyl fluoride with fluoro alcohols in the presence of sodium fluoride or cesium fluoride are used to prepare sulfinates [521 (equadon 30) (Table 12). 

This nucleophilic replacement of halogen atoms proceeds under mild conditions due to the neighboring azo group and the presence of copper ions. The o-sulfonic acid group is also susceptible to the copper-mediated nucleophilic substitution, and other nucleophiles, such as alkoxy, alkylamino, cyano, and sulfinic acid can also replace the halogen atom in the position ortho to the azo group in the presence of copper ions. 

Unlike many other type of radical addition reactions, the product is most often an alkyl-cobalt(III) species capable of further manipulation. These product Co—C bonds have been converted in good yields to carbon-oxygen (alcohol, acetate), carbon-nitrogen (oxime, amine), carbon-halogen, carbon-sulfur (sulfide, sulfinic acid) and carbon-selenium bonds (equations 179 and 180)354. Exceptions to this rule are the intermolecular additions to electron-deficient olefins, in which the putative organocobalt(III) species eliminates to form an a,/ -unsaturated carbonyl compound or styrene353 or is reduced (under electrochemical conditions) to the alkane (equation 181)355. 

Less frequently the sulfonic acid group is introduced indirectly (6) byreplacing a halogen atom with the sulfonic acid group by means of sodium sulfite (7) by the action of bisulfite on a nitro compoimd or on a quinone or quinoneoxime (nitrosophenol) (8) by oxidation of a sulfinic acid, a mercaptan, or a disulfide and (9) by the introduction of the —CH2SO3H group by means of formaldehyde-bisulfite. 

Salts of sulfinic acids ace converted to sulfones by the action of pri-lary/ secondary, and benzyl halides, alkyl sulfates, and aryl halides in which the halogen atoms are activated by nitro groups in the ortbo or para positions. The reaction fails with t-amyl halide. The yields vary widely, depending upon the nature of the reactants. From salts of benzenesulfinic acid and simple alkylating agents, sulfones are produced in 50-90% yields. Satisfactory results have been obtained when the aryl sulfinic acid contains nitro, cyano, and acetamido groups. Keto sulfones are made in 48-62% yields by alkylation with a-halo ketones. ... 

Sulfinic acids and sulfoxides are not particularly common, being readily oxidized to the sulfonic acids and sulfones, respectively. Sulfonic acids have high melting points and probably exist as zwitterions. They are amphoteric, but mainly display the characteristics of weak acids. The sulfonic acid group activates an adjacent halogen to nucleophilic displacement, and may itself be displaced, e.g. reaction of alkylamines with benzimidazole-2-sulfonic acid. Imidazolesulfonic acids resist esterification and acid chloride formation, and are only hydrolyzed by concentrated hydrochloric acid at 170 °C the 2-isomers are more resistant than the 4- or 5-isomers. Aqueous alkali converts the free acids into hydroxy derivatives. Sulfonyl chlorides are accessible via the thiols (Section 4.07.3.6.1) which react with ammonia to form sulfonamides, or are reduced by tin(II) chloride to thiols (77JHC889). 

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