Sulfinylation

In sulfoxides and sulfones an adjacent CH group is also deprotonated by strong bases. If one considers the sulfinyl (—SO—) or sulfonyl (—SOj—) groups to be functional groups, then these carbanions are d -synthons. It will be shown later (p. 48f. and 65f.), that these anions may either serve as nonfunctional, d -, d - or d -synthons. 

In order to make these oxidative reactions of 1,3-dienes catalytic, several reoxidants are used. In general, a stoichiometric amount of benzoquinone is used. Furthermore, Fe-phthalocyanine complex or Co-salen complex is used to reoxidize hydroquinone to benzoquinone. Also, it was found that the reaction is faster and stereoselectivity is higher when (phenylsulflnyl)benzoquinone (383) is used owing to coordination of the sulfinyl group to Pd, Thus the reaction can be carried out using catalytic amounts of PdfOAcji and (arylsulfinyl)benzoquinone in the presence of the Fe or Co complex under an oxygen atmosphere[320]. Oxidative dicyanation of butadiene takes place to give l,4-dicyano-2-butene(384) (40%) and l,2-dicyano-3-butene (385)[32l]. 

Sulfoxides. Sulfoxides, R — SO—R, are named by placing the names of the radicals in alphabetical order before the word sulfoxide. Alternatively, the less senior radical is named followed by sulfinyl- and concluded by the name of the senior group. For example, CH3CH2—SO—CH2CH2CH3 is named either ethyl propyl sulfoxide or l-(ethylsulfinyl)propane. 

The N-oxides of isoquinolines have proved to be excellent intermediates for the preparation of many compounds. Trialkylboranes give 1-alkyl derivatives (147). With cyanogen bromide in ethanol, ethyl N-(l- and 4-isoquinolyl)carbamates are formed (148). A compHcated but potentially important reaction is the formation of 1-acetonyLisoquinoline and 1-cyanoisoquinoline [1198-30-7] when isoquinoline N-oxide reacts with metbacrylonitrile in the presence of hydroquinone (149). Isoquinoline N-oxide undergoes direct acylamination with /V-benzoylanilinoisoquinoline salts to form 1-/V-benzoylanilinoisoquinoline [53112-20-4] in 55% yield (150). A similar reaction of AJ-sulfinyl- -toluenesulfonamide leads to l-(tos5larriino)isoquinoline [25770-51-8] which is readily hydrolyzed to 1-aminoisoquinoline (151). 

Sulfoxides are compounds that contain a sulfinyl group covalendy bonded at the sulfur atom to two carbon atoms. They have the general formula RS(0)R, ArS(0)Ar, and ArS(0)R, where Ar and Ar = aryl. Sulfoxides represent an intermediate oxidation level between sulfides and sulfones. The naturally occurring sulfoxides often are accompanied by the corresponding sulfides or sulfones. The only commercially important sulfoxide is the simplest member, dimethyl sulfoxide [67-68-5] (DMSO) or sulfinylbismethane. 

Sulfoxides occur widely in small concentrations in plant and animal tissues, eg, aHyl vinyl sulfoxide [81898-53-5] in garlic oil and 2,2 -sulfinylbisethanol [3085-45-8] as fatty esters in the adrenal cortex (1,2). Homologous methyl sulfinyl alkyl isothiocyanates, which are represented by the formula CH3SO(CH2) NCS, where n = 3 [37791-20-1], 4 [4478-93-7], 5 [646-23-1], 8 [75272-81-0], 9 [39036-83-4], or 10 [39036-84-5], have been isolated from a number of mustard oils in which they occur as glucosides (3). Two methylsulfinyl amino acids have also been reported methionine sulfoxide [454-41-1] from cockroaches and the sulfoxide of i -methylcysteine, 3-(methylsulfinyl)alaiiine [4740-94-7]. The latter is the dominant sulfur-containing amino acid in turnips and may account in part for their characteristic odor (4). 

Displacement of the sulfinyl group of penems (85), obtained by regio selective oxidation of (74, R = R" = CH2CHCH2) (Fig. 5)... 

Benzisothiazoles are formed by the action of ammonia or amines on benzenesulfenyl halides bearing an o-carbonyl function (72AHC 14)43, 80MI41700). Analogous diphenyl disulfides behave similarly (77SST(4)339). Sulfinyl chlorides or phenylsulfoxides produce... 

Chloro-a,/3-unsaturated aldehydes condense with ammonium thiocyanate to give isothiazoles (76EGP122249). 2,3-Diphenylcyclopropenone reacts with iV-sulfinyl-cyclohexylamine in the presence of nickel tetracarbonyl to give the isothiazolin-3-one 1-oxide (197) (79SST(5)345). Cholesteryl acetate reacts with trithiazyl trichloride in pyridine to give the isothiazolo steroid (198) (77JCS(P1)916). 

Section 5.10.3.2). Treatment of methyl 6-phthalimido penicillinate (jR)-sulfoxide (40) with JV-chlorosuccinimide in refluxing carbon tetrachloride gives an epimeric mixture of sulfinyl chlorides (41) which are ring closed to epimeric 3-methylenecepham sulfoxides (42a) using tin(IV) chloride. Reduction with phosphorus tribromide gives the desired methyl 7-phthalimido-3-methylenecepham 4-carboxylate (42b). 

Alkanesulfinyl chlorides have been prepared by the action of thionyl chloride on alkanesulfinic acids and by the solvolysis of alkylsulfur trichlorides with water, alcohols, and organic acids. The present procedure, which appears to be general for the preparation of sulfinyl chlorides in either the aliphatic or the aromatic series, is based on an improvement in the solvolysis method whereby the use of inert solvent is eliminated and the reaction is carried out in a one-phase system. ... 

When there is an a-hydrogen in the sulfide, the sulfuranes are unstable and cannot be isolated [775]. Sulfoxides [776] and sulfinyl fluorides [777] are oxidatively fluorinated with tluorine to give hexavalent sulfur compounds in yields up to 90%. 

From semiamidals, the correspondmg tnfluoromethyl substituted N-acyl mines [25, 28], 1,3-diambutadienes [27], N-sulfonyl mines [5, 29], N sulfinyl mines [30], and N-phosphoryl mines [31] can be obtamed in high yields on reaction with powerful dehydratmg realms like POC -pyndine or tnfluoroacetic anhydnde-pyndme [2, 5]... 

Sulfinyl azides have higher thermal stability than their divalent counterparts. For example, benzenesulfmyl azides ArS(0)N3 (Ar = Ph, 4-MeCelFt, 4-NO2C6H4), which are obtained by the metathetical reaction of the sulfinyl chloride and sodium azide in acetonitrile, can be stored in the solid state at low temperatures. ... 

Reactions with Sulfonyl Chlorides, Sulfinyl Chlorides,... 

Hydrogen chloride has also been eliminated from sulfinyl chlorides by addition of triethylamine. The thioketone oxide obtained from 9-fluorene-sullinyl chloride reacted with morpholinocyclohexene to give a zwitterionic adduct (475). 

Also notable are sulfur cyanide fluorides such as SF3CN,( 4°> SF2(CN)2 ° and SFjCN - ) and the sulfinyl cyanide fluoride FS(0)CN. " ° ... 

The Darzens condensation reaction has been used with a wide variety of enolate equivalents that have been covered elsewhere. A recent application of this important reaction was appljed toward the asymmetric synthesis of aziridine phosphonates by Davis and coworkers.In this application, a THF solution of sulfinimine 34 (0.37 mmol, >98% ee) and iodophosphonate 35 (0.74 mmol) was treated with LiHMDS (0.74 mmol) at -78 °C to give aziridine 36 in 75% yield. Treatment of 36 with MeMgBr removed the sulfinyl group to provide aziridine 37 in 72% yield. 

A -sulfinyl chiral auxiliaries have been used to prepare enantiopure tetrahydro-P-carbolines and tetrahydroisoquinolines in good yields under mild reaction conditions. Both enantiomers of V-p-toluenesulfinyltryptamine 46 could be readily prepared from the commercially available Andersen reagents.Compound 46 reacted with various aliphatic aldehydes in the presence of camphorsulfonic acid at -78 °C to give the A-sulfinyl tetrahydro-P-carbolines 47 in good yields. The major diastereomers were obtained after a single crystallization. Removal of the sulfinyl auxiliaries under mildly acidic conditions produced the tetrahydro-P-carbolines 48 as single enantiomers. 

The activation energies were computed to 3.0 (toward 183), 0.3 (toward 182), and 21.8 kcal/mol (toward 184) at the B3-LYP/6-31G level, and thus the mechanism leading to 182 is the preferred one. The transition states of all three reactions belong to concerted but asynchronous reaction paths. The transacetalization of 177 with acylium cations results in the formation of the thermodynamically stabilized 187 (Scheme 121) [97JCS(P2)2105]. 186 is less stable than 187, and 185 is destabilized by 32.5 kcal/mol. Moreover, transacetalization of 177 with sulfinyl cations is not a general reaction. Further computational studies on dioxanes cover electrophilic additions to methylenedioxanes [98JCS(P2)1129] and the influence... 

Asyrrunetiic Diels-Alder reacdons using chuMsulfinylalkenes have been extensively snidied by Koiziuru and coworkers Fuji and coworkers have extended this strategy to chirM 1-falkyl-sulfinyl -2-nitroalkenes Such nltroalkenes react v/ith reacdve dienes such as Danishefsky s dienes to produce an adduct v/ith a high enandomeric excess fee fsee Eqs 8 34 and 8 35 ... 

Ruano has reported substrate-controlled asymmetric ylide aziridination by treatment of enantiopure sulfinyl imines 117 with dimethyloxosulfonium methylide 118 to form terminal aziridines [63], The chiral tert-butylsulfinyl group was shown... 

More recently, Davis and co-workers developed a new method for the asymmetric syntheses of aziridine-2-carboxylates through the use of an aza-Darzens-type reaction between sulfinimines (N-sulfinyl imines) and a-haloenolates [62-66]. The reaction is highly efficient, affording cis- N-sulfmylaziridine-2-carboxylic esters in high yield and diastereoselectivity. This method has been used to prepare a variety of aziridines with diverse ring and nitrogen substituents. As an example, treatment of sulfinimine (Ss)-55 (Scheme 3.18) with the lithium enolate of tert-butyl bromoacetate gave aziridine 56 in 82% isolated yield [66],... 

The Stockman group has also studied reactions between the same imines and allyl sulfonium ylides (first reported by Hou and Dai [45]) [46], N-Sulfinyl vinylazir-... 

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