Cyano selenides

Nitrites. Allylic cyanides are formed from the acetates or carbonates in (PhsPjaPd-catalyzed transformations. Intramolecular cyanosilylation of alkynes provides a way of controlled functionalization of such compounds using a tether tac- a-Cyano selenides are products from SnCU-catalyzed reaction of diselenoacetals with MeiSiCN. Seleno-ortho esters also exchange one seleno group for the cyanide. ... 

Cyanosehnenylation of aldehydes. Aldehydes react with aryl selenocyanates in the presence of tri-n-butylphosphine in THF at 20° to form cyano selenides in 75-99% yield (equation I). Ketones do not undergo this reaction. The products can be used for a variety of transformations, as formulated in equations (II) and (HI). 

Cyano-substituted selenophenes are valuable precursors of formyl derivatives.89 They are also used as starting materials for the preparation of carboxylic acids and their derivatives.128 By treating the cyano compounds with hydrogen selenide, selenoloamides (101) were obtained. As shown in... 

Treatment of MFA (1) with cyanogen bromide [6] opened ring G to yield the bromo derivative 3 [7]. Attempts to dehydrobrominate 3 in one step via a base-catalyzed elimination with DBU/CH3CN, KOH/MeOH, or terr-BuOK/DMSO were unsuccessful. However, the required methylene entity could be introduced by converting 3 first to a selenide, then oxidation with periodate, followed by thermolysis in benzene to provide compound 4. Hydrolysis of the cyano group with NaOH in ethylene glycol [8] produced 5 (50% yield). Osmium catalyzed oxidation of 5 in the presence of 4-methylmorpholine A-oxide (NMO) gave a diol, which was cleaved to an aldehyde upon treatment with periodate. Treatment of the aldehyde with sodium cyanoborohydride resulted in an intramolecular reductive animation to yield the desired product PHB (6). 

Related to these reacations is the anodic methoxylation of sulfides carrying an electron-withdrawing substituent, such as cyano [105], fluoromethyl [106], difluoromethyl [106], or trifluoromethyl [106-109] in the a-position [Eq. (41)]. Yields are typically between 50 and 90%. An analogous reaction has been reported for selenides carrying electron-withdrawing perfluoroalkyl or cyano substituents [110]. 

Anodic monofluorination of selenides bearing electron-withdrawing cyano and ester groups can be performed in an undivided cell, while the fluorination of a-selenoamide requires an anion-exchange membrane diaphragm [51] ... 

Grignard and organolithium reagents were competent nucleophiles for the reaction (entries 1-7) but less basic thiolate and selenide nucleophiles were also effective (entries 8-10). The cyano and azido derivatives (entries 11 and 12 respectively), prepared from the trimethylsilyl precursors, were further functionalised yielding o-heterocyclic derivatives (Scheme 5.11). 

Photonucleophilic aromatic substitution reactions of phenyl selenide and telluride with haloarenes have also been proven to involve the S jlAr mechanism, with the formation of anion radical intermediates. Another photonucleophihc substitution, cyanomethylation, proves the presence of radical cations in the reaction mechanism. Liu and Weiss have reported that hydroxy and cyano substitution competes with photo substitution of fluorinated anisoles in aqueous solutions, where cation and anion radical intermediates have been shown to be the key factors for the nucleophilic substitution type. Rossi et al. have proposed the S j lAr mechanism for photonucleophihc substitution of carbanions and naphthox-ides to halo anisoles and l-iodonaphthalene. > An anion radical intermediate photonucleophilic substitution mechanism has been shown for the reactions of triphenyl(methyl)stannyl anion with halo arenes in liquid ammonia. Trimethylstannyl anion has been found to be more reactive than triphenylstannyl anion in the photostimulated electron- transfer initiation step. 

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