Sulfides, allyl reaction with allylic bromides

It is well known that aziridination with allylic ylides is difficult, due to the low reactivity of imines - relative to carbonyl compounds - towards ylide attack, although imines do react with highly reactive sulfur ylides such as Me2S+-CH2-. Dai and coworkers found aziridination with allylic ylides to be possible when the activated imines 22 were treated with allylic sulfonium salts 23 under phase-transfer conditions (Scheme 2.8) [15]. Although the stereoselectivities of the reaction were low, this was the first example of efficient preparation of vinylaziridines by an ylide route. Similar results were obtained with use of arsonium or telluronium salts [16]. The stereoselectivity of aziridination was improved by use of imines activated by a phosphinoyl group [17]. The same group also reported a catalytic sulfonium ylide-mediated aziridination to produce (2-phenylvinyl)aziridines, by treatment of arylsulfonylimines with cinnamyl bromide in the presence of solid K2C03 and catalytic dimethyl sulfide in MeCN [18]. Recently, the synthesis of 3-alkyl-2-vinyl-aziridines by extension of Dai s work was reported [19]. 

California Red Scale is a worldwide citrus pest which can be controlled by means of the pheromone 60. Cohen used reductive lithiation to generate versatile allylic nucleophiles applicable to this type of target.6 The allyl sulfide 61 is lithiated by BuLi and reacts with butenyl bromide a to sulfur to yield 63. Reductive lithiation (Li, DBB) of the product yields allyllithium 64. A regioselective reaction of this nucleophile with formaldehyde at the more substituted terminus is ensured by transmetallation to the allyl titanium 65, which gives 66 after treatment with formaldehyde and bromination. 

Allyl halides are also alkylated by zinc cyanocuprates. Allylic bromides, iodides and chlorides react successfully with these reagents, and a number of functional groups in the allylic halide (ester, sulfide, sulfoxide, ether, alkyl halides, acetals) stand up well to the conditions of reaction (equations 29 and 30)41 3. The regiochemistry of attack is predominantly Sn2. 1,3-Dichloroalkenes can be made to undergo two successive coupling reactions to this point, only two identical R group incorporations have been reported (equation 31)44. 

Perfluoroaryl alkyl sulfides (e.g., 7) can be synthesized by the reaction of Grignard reagents with aryl halides in the presence of elemental sulfur. For example, allyl pentalluorophenyl sulfide (7) is obtained in excellent yield from bromopentafluorobenzene (5) and allyl bromide... 

Takei [88] examined the catalytic activity of Pd(PPh3)4 and PdCl2(PPh3)2 on the reaction of phenylmagnesium bromide with allyl isopropyl sulfide the alkylated products were... 

Allyl-allyl cross-coupling of allyl bromides (Structure 1) and allyl sulfides (2) carrying homoallylic alcohol or ester functions takes place under irradiation with hexamethylditin (see eq. (1)). The reaction cleanly leads to 2,6-dienes (3) and no isomerization of allylic bromides is oberserved [56]. 

Diorganochakogenides. A method for synthesis of allyl sulfides and selenides involves formation of allylsamarium bromide and its reaction with PhX-XPh (X=S, Se) in THF. For a similar approach to benzyl sulfides, the benzylsamarium halides are formed in the presence of BiClj. Aqueous media can be used in this latter reaction. 

Etherification of hindered tribromophenol with allyl bromide Reaction of sodium sulfide with benzyl chloride Reaction of amino acids and methanesulfonyl chloride Dichlorovinylation of carbazole in solid-liquid system... 

Knochel and co-workers have carried out a series of nucleophilic substitution reacion on ( )-allyl bromide using thiolate ions. The reaction between bromide 326 and lithium phenylthiolate yielded the ( )-sulfide 327 exclusively. However, treatment of ( )-sulfide 327 with the more nucleophilic reagent sodium methyl thiolate led to a 20 80 mixture of 327 and ( )-methyl sulfide 328. They proposed that either a S- 2 mechanism is operative, or two S- 2 substitutions eventually resulted in the thermodynamically more stable sulfide (ii)-methyl sulfide 328. A similar reaction of 326 with aniline in excess or its chloromagnesium amide gave a mixture of 5 n2 and 5 n2 products 329 and 330 which slowly equilibrate to give S-f 2 product 329 in 78% yield (Scheme 3.143). 

To a suspension of 1.10 mmol of eopper(I) bromide-dimethyl sulfide in 2 mL of THF arc added 2.20 mmol of Bul.i in hexane at — 70 C und the clear solution is stirred at — 40°C for 40 min. 1.15 mmol of freshly fused zinc(Il) chloride dissolved in THF (1 M, 1.15mL) are added at - 70°C and after 15 min 1.0 mmol of the allylic halide in 1 mL of 1HF are added. After 15 h at -702C, the reaction mixture is diluted with hexane washed with sat. aq NaHC03 and sat. aq NaCI and then dried over MgS04. Tile solvent is removed, the product ratio analyzed by GC and the product is purified by chromatography. 

Allylation of all these species is apparently less selective (Scheme 69, entry a), and among the various thioacetals tested 1,3-dithianes proved to be the ones which lead to the highest 0 7 The use of HMPA as a cosolvent was shown to have no effect on the regioselectivity of the allylation. However, both exclusive 7-allylation and 7-methylation have been achieved by performing the reaction in the presence of copper(I) iodide-trimethyl phosphite complex (Scheme 69, entries a-e). The reaction is best achieved with allylic chlorides, bromides and phosphate esters and does not occur with acetates, although these compounds usually react with cuprates. In all cases where isomers could be formed with respect to the electrophile, the ratio of 5n2 5n2 products was found to be greater than 0.67 (Scheme 69, entries b-e).- Related reactions have already been described with allylic sulfides (Scheme 27, see Section 1.3.2.2.4). 62.iM... 

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