Ketones sulfenylation

The enamino ketone 49 has also been found to react with o-nitrobenzene-sulfenyl chloride to give the derivative 156, having the o-nitrophenylthio group substituted in the 2 position (93), i.e., the same position at which normal acylation with acid chlorides takes place. 

Tlie bifunctional sulfenyl chloride 213 was obtained by chlorination of 144 in good yield, although excessive chlorination led to the saturated compound 214 (94CB533). A series of compounds 215-220 were obtained from 213 by reactions with secondary amines ferf-butyl methyl ketone hexane-2,4-dione 2,6-dimethylcyclohexanone diethyl malonate and acetylacetone, respectively. 

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... 

Sulfenylation, Sulfonation, and Selenylation of Ketones and Carboxylic Esters... 

In the reaction of ketones with thionyl chloride the intermediate sulfinyl (or sulfenyl) chloride can cyclize on to an aromatic ring located two carbon atoms away giving benzo[b]thiophenes (48) (Scheme 7).54 Additional... 

Asymmetric sulfenylation. In the presence of the chiral diamine (S)-l-methyl-2-(piperidinylmethyl)pyrrolidine (1), tin(II) enolates of ketones react with... 

Addition of halogens or interhalogens to perfluorohalogenothio-ketones, as already described, represents an important method for the preparation of complex sulfenyl halides. 

Thionyl chloride undergoes a cyclization reaction with ketones. Enoli-zation of the intermediate sulfenyl chloride, followed by the base-induced intramolecular nucleophilic displacement reaction, produces the thietanone... 

The a-sulfenylation of ketones has received much attention as it can be employed in a variety of synthetically useful reactions [38. 213]. Oxidation to the sulfoxide followed by the syn elimination just described leads to an a,(3-unsaturated ketone. 

Styrene 29 Styrene oxide 144 (E )-Styryl p-tolyl sulfone 29 Sulfates from diols 59 Sulfenylation of ketones 54,66 Sulfides... 

The introduction of a-heteroatom functionalization into an aldehyde or ketone is a very useful class of transformation. Performing it directly and asymmetrically, using organocatalysts, has been reviewed for reactions such as amination, oxygenation, halo- genation, and sulfenylation (44 references).260... 

In this chapter, we will outline the application of organocatalysis for the enantio-selective a-heteroatom functionalization of mainly aldehydes and ketones. Attention will be focused on enantioselective animation-, oxygenation-, fluorination-, chlorination-, bromination-, and sulfenylation reactions catalyzed by chiral amines. The scope, potential and application of these organocatalytic asymmetric reactions will be presented as the optically active products obtained are of significant importance, for example in the life-science industries. 

In the following sections we will describe recent developments and applications in the organocatalytic a-heteroatom functionalization of aldehydes and ketones catalyzed by chiral amines [1]. Notably, the C-H to C-Het transformations associated with amination, oxygenation, halogenation (fluorination, chlorination, bro-mination), and sulfenylation will be outlined (Scheme 2.24). 

Fluoro 6 chloro acetophenone see 2 Fluoro phenacyl chloride 4 Fluoro 2 chloro benzophenone see 2 Chloro phenyl 4 fluoro phenyl ketone Fluoro dichloro methyl sulfenyl chloride dichlorofluanid... 

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). ... 

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