Benzeneselenyl chloride

Benzeneselenenyl chloride (benzeneselenyl chloride, phenylselenenyl chloride) [5707-04-0] M 191.5, m 59-60 , 64-65 , b 92 /5mm, 120 /20mm. Purified by distn in vac and recrystn (orange needles) from hexane [Foster J Am Chem Soc 55 822 1933, Foster et al. Reel Trav Chim, Pays-Bas 53 405, 408 1934-, Behaghel and Seibert Chem Ber661 4 1933.] HIGHLY TOXIC. 

Benzeneselenyl chloride added to (+)-7 and gave adduct 119 nearly quantitatively. Treatment with N-methvl-N-tertbutvldimethvlsilvltrifluoroacetamide and triethylamine (dimethylformamide, molecular sieves, 40 °C, 15 h) afforded enol ether 120 in high yield (>90 %). Oxidation with an excess of MCPBA gave 121... 

In the reactions of the perhydro-l,3-benzoxazine derivatives 236 with benzeneselenyl chloride in dichloromethane-methanol, methoxyselenylation of the double hond in the C-2 side chain occurred in a highly regio- and diastereo-selective way (Scheme 43). Reductive deselenylation of 237 with triphenyltrn hydride in the presence of a catalytic amount of azobisisobutytonitrile (AIBN) resulted in formation of the methoxy derivatives 238 <2006JOC2424>. 

The 4-hydroxy-(S)-proline-derived acid (232) was subjected to electrophilic lactoni-zation either with J2-KJ-NaHC03 to yield the iodolactone (233a), or benzeneselenyl chloride to give the phenylselenolactone (23b). Reductive removal of X from these products was achieved with tri-n-butyl- or triphenyltin hydride, followed by hydro-genolysis to yield (234) with at least 99% optical purity 231 j). 

Direct reaction of benzeneseleninyl chloride (prepared by ozonization of benzeneselenyl chloride) with olefins in presence of A1C13 yields vinyl chlorides (equation 145)956 ... 

Selenoxides are useful intermediates in the preparation of a,3-unsat-urated carbonyl compounds and esters. The treatment of aldehydes, ketones, or esters with benzeneselenyl chloride, C6H5SeCl, followed by the oxidation of the selenides to selenoxides by hydrogen peroxide, peroxy acids, or sodium periodate, gives a,3-unsaturated aldehydes, ketones, or esters. Thus, dehydrogenation with the formation of a carbon-carbon double bond is accomplished under very mild conditions [167, 169] (equation 593). 

To a solution of 5.50 g (14.2 mmol) of 3-cholestanone in 125 mL of ethyl acetate is added 3.30 g (17.2 mmol) of benzeneselenyl chloride (CsHsSeCl), and the red-orange solution is stirred for 1 h until it turns pale yellow. Water (25 mL) is added to the stirred mixture, the aqueous layer is drained, and to the organic phase is added 55 mL of tetrahydrofuran and, dropwise, 3.5 mL (34.3 mmol) of 30% hydrogen peroxide while the mixture is stirred for an additional hour at a temperature below 35 °C. The reaction mixture is washed with water and a solution of sodium carbonate, dried, and evaporated to give 5,25 g (96%) of crude product, which on recrystallization from ethanol furnishes 2.43 g (45%) of l-cholesten-3-one, mp 95-97 °C. 

Nitroestrone has been obtained in 79% yield by the addition of estrone to molar proportions of benzeneselenyl chloride and silver nitrate in acetonitrile followed by reaction with stirring for 3 hours at ambient temperature (ref.64). 

Benzeneselenyl chloride added to startg. urea in chloroform containing silica gel under argon, and the suspension stirred at 25° for 9 h - product. Y 92%. F.e. and stereospecificity s. C. Betancor et al., J. Chem. Soc. Chem. Commun. 1989, 450-2. 

Phenyl selenocyanate is an important reagent for organic synthesis, capable of a wide variety of selenylation reactions. Until now the method of preparation has employed a diazo reaction however, in a new synthesis benzeneselenyl chloride reacts with trimethylsilyl cyanide to give phenyl selenocyanate in quantitative yield (Scheme 54). Since isolation simply involves evaporation of the solvent, this reaction represents a very simple synthesis of the useful reagent. 

Furthermore an intriguing observation on the conversion was that after the rapid addition of benzeneselenyl chloride to the olefin, the subsequent amination step was slow, but could be facilitated by the presence of silica The benzeneselenyl moiety also represents a. very useful handle to the molecule for further conversions. This excellent method only seems to be spoiled by one thing, where two ring sizes are possible, both may be produced, for example (259) gave rise to a 51 49 mixture of (260) and (261) in 76% total yield. 

Cycloheptene-l-methanol treated at -78 with 1.1 equivalents benzeneselenyl chloride in methylene chloride cyclic phenylselenoether. Y 95%. F. e. and reactions of the products s. K. C. Nicolaou and Z. Lysenko, Tetrah. Let. 1977, 1257 Chem. Commun. 1977, 331. 

Nucleophilic substitution, e.g. the preparation of thiocyanates from lipophilic alcohols, can be facilitated by substrate hydrophilation via ammonioethanesulfonic acid esters (betylates)i . Mercaptans can be easily prepared from alcohols with inversion of configuration via thiolic esters prepared with thioacetic acid in the presence of 2-fluoro-pyridinium salts . C-Sulfenylation of / -dicarbonyl compounds with mercaptans by air oxidation in the presence of tetraethylammonium fluoride has been reported . Activated thiolic and selenolic esters can be prepared at room temperature from carboxylic acids and aryl thiocyanates or selenocyanates in the presence of tri-n-butylphosphine i. Phenylselenolactones have been obtained under very mild conditions from unsaturated acids and benzeneselenyl chloride. ... 

The reaction of trialkylalkynyl borate salts with benzeneselenyl chloride followed by selective oxidation constitutes a new synthetic pathway from alkynes to acyclic a,/3-unsaturated ketones. The latter method is especially useful for the preparation of unsymmetrical acyclic enones (Scheme 27). ... 

Ruggiu AA, Lysek R, Moreno-Clavijo E, Moreno-Vargas AJ, Robina I, Vogel P. The regioselectivity of the addition of benzeneselenyl chloride to 7-azanorbom-5-ene-2-yl derivatives is controlled by the 2-substituent new entry into 3-and 4-hydroxy-5-substituted prolines. Tetrahedron 2010 66 (36) 7309-7315. 

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