Selenoxide, diphenyl

No oxidizing agent is required for the sulfuric acid promoted cyclization of iV,iV-diphenyl-hydroxylamine to carbazole (13CB3304). The parallel conversion of diphenyl sulfoxide and diphenyl selenoxide to dibenzothiophene (23CB2275) and dibenzoselenophene (39CR(199)53l) is effected by treatment with sodamide. 

DIHYDROXYLATION Osmium tetroxide-Dihydroquinine acetate. Osmium tetrox-ide-Diphenyl selenoxide. Osmium tetroxide-Trimethylamine N-oxide-Pyiidine. Thallium(l) acetate-iodine. Triphenylmethylphosphonium permanganate. 

Sulfuric acid promotes cyclization of (V./V-diphenylhydroxylamine (14) to carbazole (11) (13CB3306). The parallel conversions of diphenyl sulfoxide (15) and diphenyl selenoxide to dibenzothiophene (10) (23CB2275) and dibenzoselenophene (39CR(i99)53i) are effected by sodamide. 

Dibenzoselenophene has been obtained by the sodamide promoted cyclization of diphenyl selenoxide (153) (34CR(l99)53l), and via diazotization of o-aminodiphenyl selenide (154) (39JCS151). 

Diphenyl selenium dichloride, (C6H5)aSeCl2, is formed when diphenyl selenoxide is treated with hydrochloric acid. It crystallises in glistening prisms, M.pt. 179° to 180° C.4 A similar product is obtained when diphenyl selenide is dissolved in an excess of concentrated nitric acid and concentrated hydrochloric acid added.5... 

Diphenyl selenoxide, (C6H5)2SeO.—This oxide may be prepared in several ways (1) Diphenyl selenium dichloride is treated with sodium hydroxide.6 (2) Diphenyl selenium dibromide is allowed to react with sodium hydroxide.7 (3) 7 grams of diphenyl selenide are slowly treated with 10 c.c. of 46 perhydrol. 8 (4) Diphenyl selenoxide... 

The readily available reagent diphenyl selenoxide has been used as a mild and selective oxidant in the synthesis of aporphines (and homoaporphines). When the benzylisoquinoline (13) was treated with one equivalent of the reagent at room temperature in methanol, and the product was O- methylated with diazomethane, the aporphine (14) was obtained in 80% yield. The alternative use of chloranil, which is a commonly used oxidant for catechols, yielded less than 10% of (14).20... 

Oxidation of A-diethylphosphito to A-diethylphosphono derivatives 151 has been performed using 2-picoline A-oxide, MCPBA, diphenyl selenoxide, or 7-butyl hydroperoxide (TBHP). The latter was selected as the most efficient reagent. Similarly, the N-phosphitylated /3-sultams undergo reactions of oxidative addition of elemental sulfur and selenium giving 2-thio- and 2-selenophosphono /3-sultams 152 and 153, respectively, in satisfactory yields (Scheme 46) <1999HAC61>. 

Tanaka H, Ishihara M, Ichino K, Ito K (1988) Synthesis of Natural Coumarinolignans Oxidative Coupling of 7,8-Dihydroxycoumarins and Phenylpropenes in the Presence of Diphenyl Selenoxide. Heterocycles 27 2651... 

QUINONES Benzeneseleninic anhydride. Diphenyl selenoxide. l-Methoxy-3-methyl-l-trimethylsilyloxy-1,3-butadiene. 

Oxidation of catechols. In accordance with earlier reports, diphenyl selenoxide selectively oxidizes o- and p-hydroquinones and has no efiect on simple phenols. An example is the oxidation of 3,5-di-f-butyIcatechol in methanol at 0° to the corresponding o-quinone, possibly via a selenurane (a) (equation I). 

Although the first alkynylselenonium salt, ethylmethylphenylethynyl sele-nonium picrate,was prepared as early as 1965 [10], it is only very recently that the first reactions of selenonium salts have been reported [11]. Among these salts, acyclic dimethyl(phenylethynyl)selenonium tetrafluoroborate (9) was prepared by methylation of methyl phenylethynyl selenide (10) with Meer-wein s reagent. The acyclic derivative 11 and the cyclic analogue 12 were synthesized by treatment of trimethyl(phenylethynyl)silane (13) and triflu-oromethanesulfonic anhydride with diphenyl selenoxide (14) and dibenzose-lenophene 5-oxide (15), respectively (Scheme 2). 

Quinoxaline is alkylated with selenuranes, which are formed by the reaction of diphenyl selenoxide and carboxylic anhydrides, under irradiation. This reaction is presumed to proceed by a radical pathway accompanying decarboxylation. 

Likewise, diphenyl selenoxide has been shown to convert aromatic amines to the corresponding azobenzenes, while, in contrast to their sulfur analogs, benzeneseleninic acid and its anhydride are well established as versatile oxidants in organic chemistry. ... 

Diphenyl selenide is oxidized with peroxyacetic acid at room temperature to diphenyl selenoxide hydrate, C6H5Se(OH)2, in 43% yield after 2 h [1198]. Benzyl phenyl selenide is oxidized to benzyl phenyl selenoxide by sodium periodate in aqueous methanol at 0 °C in 95% yield and by iodobenzene dichloride in aqueous pyridine at -40 °C in 85% yield [773]. 

Diphenyl selenoxide has been advocated for the oxidation of catechols to ortho-quinones in the synthesis of benzylisoquinoline alkaloids. ... 

Diphenyl selenoxide Oxidations with selenoxides Oxidative dimerization... 

---