Amides sulfenylation

Many other reactions of ethylene oxide are only of laboratory significance. These iaclude nucleophilic additions of amides, alkaU metal organic compounds, and pyridinyl alcohols (93), and electrophilic reactions with orthoformates, acetals, titanium tetrachloride, sulfenyl chlorides, halo-silanes, and dinitrogen tetroxide (94). 

A heterocyclic ring may be used in place of one of the benzene rings without loss of biologic activity. The first step in the synthesis of such an agent starts by Friedel-Crafts-like acylation rather than displacement. Thus, reaction of sulfenyl chloride, 222, with 2-aminothiazole (223) in the presence of acetic anhydride affords the sulfide, 224. The amine is then protected as the amide (225). Oxidation with hydrogen peroxide leads to the corresponding sulfone (226) hydrolysis followed by reduction of the nitro group then affords thiazosulfone (227). ... 

From intermediate 12, the path to periplanone B (1) is short but interesting. Enolization of 12 with lithium bis(trimethylsilyl)amide at -78 °C, followed by sulfenylation using Trost s reagent,12 affords a 16 1 mixture of regioisomeric monosulfenylated ketones favoring intermediate 17. The regioselectivity displayed in this reaction is... 

A monodentate palladium(II) complex trans-[Pd(py)2(H202)]2+ hydrolyzes Met-Aa amide bonds with a rate comparable with that promoted by [Pd(H20)3(0H)]+. Unlike Pd(H20)3(0H)]+, //chelated complex containing temed (A,A,AAA -tctramcthylcthylenediamine) hydrolyzes Met-Aa amide bonds with hydrolytic rate controlled by temed release. The action of the other two complexes, c -[Pd(ED-TA)C12] (EDTA = ethylene diaminetetraacetic acid) and cis-1,2-bis(2-formylglycinebenzene-sulfenyl)ethane Pd11 chloride differs from the action of similar complexes of U,v-[Pd(en)Cl2] and cw-[Pd(dtco-3-OH)Cl2] (dtco-3-OH = l,5-dithiacycooctan-3-ol).448... 

All acetylenes with a terminal triple bond are instantaneously converted into the alkali acetyiides by alkali amides in liquid ammonia. For many alkylations with primary alkyl halides liquid ammonia is the solvent of choice and the functionalization with oxirane can also be carried out in it with good results. Reactions of RC=CM with sulfenylating agents (R SSR R SC=N, R SSC R ) or elemental sulfur, selenium or tellurium are mostly very successful in ammonia, the same holds for the preparation of RCsCI from RGCM and iodine. The results of couplings with carbonyl compounds are very variable. 

A very general method for preparing 1,3,4-oxathiazole and 1,2,4- and 1,3,4-dithiazole derivatives from sulfenyl chlorides and amides is shown in Scheme 45, and some of this work has been reviewed (70AG(E)54). As is apparent, the nature of the sulfenyl chloride, and particularly of the amide, strongly influences the course of the reaction. 

TL 24 2009 (1983) (0-keto ester) 25 1241 (fi-diketones to /J-hydroxy ketones), 4623 (3-oxo glutarate and adipate esters), 5083 (a-sulfenyl-/J-keto esters) (1984) 26 101 (/J-keto esters), 771 (a-PhS ketone), 4213 (/J-keto esters) (1985) 27 565 (/J-diketones to /J-hydroxy ketones), 1915 (a-keto esters) 2091 (/J-keto esters), 2657 (/J-keto esters), 3547 (2-acyl- 1,3-dithianes 2-acylthiazoles), 4737 (a-chloro ketones), 4817 (a-PhSOj ketone), 5275 (/J-keto esters and amides), 5281 (/ -keto esters), 5397 (a-chloro ketone, /J-keto ester), 5405 (/J-keto thio- and dithioesters) (1986) 28 2709 (/ -chloro-a-keto ester), 3189 (/J-keto ester) (1987) 29 4769 (3- and 4-nitro ketones), 4865 (/J-keto ester), 6167 (5-acetyl-2-isoxazolines) (1988) 30 2707 (yS-keto ester), 3701, 5705 (/J-keto ester) (1989) 31 1159 (/J-keto ester), 1615 (/J-keto ester), 1811, 3631 (/J-keto esters), 4025 (a-hydroxy ketone), 4195 (2-acyl-2-alkenoate ester), 5575 (y- and 5-keto sulfones), 7463 (/J-diketone to /f-hydroxy ketone)... 

The sulfmylation of esters, - lactones, carboxylic acids, > amides and lactams may be effected by reacticm of the corresptHiding lithium enolates in THF at -78 to 0 C with dimethyl or difdie-nyl disulfides, or, less conunmily, with methyl or fdienyl sulfmyl halides. The enolates of ketones, however, are insufficioitly nucleq diilic to react with dialkyl sulfides unless HMPA is added to the re-acticm mixture, although they do react smoothly with diaryl sulfides. This difference allows the selective sulfenylation of esters in the presence of ketones (entry 5, Table 3). ... 

In contrast to the free acids, sulfenate esters, amides and halides are more stable. Disulfides (52) can be obtained from thiols by mild oxidation (see p. 57), and sulfenyl chlorides () can in turn be prepared from disulfides (52) by treatment with chlorine (Scheme 30). Sulfenyl chlorides (51) react with alcohols to give esters, e.g. the methyl sulfenate (53) which on alkaline hydrolysis yields the sulfenic acid (45) (Scheme 30). 

Sulfenic acid derivatives (RSX) such as esters, amides and halides are reactive owing to the relative weakness of the S-X bond, and they consequently react with nucleophilic reagents (Nu-) (Scheme 33). In such nucleophilic substitutions at the sulfenyl sulfur atom, the reaction mechanism may be SN1 (Scheme 34). 

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