Phenyl selenenyl chloride

The same substrate 170 reacts with alkyl(phenyl)selenenyl chlorides to give predominantly 2,5-dihydro-l,2-oxaphosphole-2-oxide derivatives 175 (Scheme 70) [150],... 

The addition of phenyl sulfenyl choride and phenyl selenenyl chloride to glycals has been investigated, which provides another entry to the 2-deoxy-P-glucosides. As summarized by Roush et al. [156] (Scheme 5.53), the method gives the best selectiv-... 

In another simple procedure, deprotonation of methoxy bis(trimethylsilyl)methane with butyl lithium and addition of the resulting anion to aldehydes induces Peterson elimination (Scheme 27). The product methyl enol ethers could be hydrolysed to the parent acyl silanes with hydrochloric acid-THF or could be treated with electrophiles such as M-halosuccinimides to give a-haloacyl silanes105. Alternatively, treatment with phenyl selenenyl chloride, oxidation at selenium and selenoxide elimination afforded a,/3-unsaturated acyl silanes. 

Total stereoselectivity was also observed on cyclization of /V -alkenyl carbamates with phenyl-selenenyl chloride to give TV-substituted piperidines 5. Due to the sense of the 1,3-asymmetric induction, cis-2,6-piperidine derivatives are obtained exclusively, their stereochemistry was assigned on the basis of H NMR107. 

BUTENOLIDES Phenyl selenenyl chloride. Phenylthioacetic acid. 7-BUTYROLACTONES Ammonium persulfate. Chromic acid, lon-exchangeresins. 

BUTENOLIDES Phenyl selenenyl chloride. Phenylthioacetic acid. 

Whereas unsaturated /3-dicarbonyl compounds are prepared easily and efficiently via a-selenenylation, particularly by the pyridine complex of phenyl-selenenyl chloride, followed by oxidative elimination of the seleno-group, the use of the less expensive selenium metal as electrophile offers obvious advantages for reactions on a larger scale [equation (33)]. ... 

Butyrolactones.—A simple method for the direct conversion of protected buty-rolactols into the corresponding butyrolactones is by oxidation with m-chloro-peroxybenzoic acid in the presence of a catalytic amount of boron trifluoride etherate. Yields are usually high but, disappointingly, the method fails with 5-lactols. Unsaturated amide (50) can be converted into the substituted buty-rolactone (51) by treatment with phenyl selenenyl chloride. The generality of this reaction remains to be established. 2-Chloro-4-alkylbutyrolactones (52 X = H or Cl) can be formed from di- or tri-chloroacetic acid respectively and alk-l-enes in the presence of dichlorotris(triphenylphosphine)ruthenium(ii). ... 

For research of synthetic opportunities of the developed approach, regio- and stereochemistry of cyclization as model substrates we used alkenes 2-7. It is necessary to note that recently in reaction of 2-pyridineselenenyl bromide analogous selenenyl chloride la with styrene 2 in methanol is received only solvoadduct - l-methoxy-l-phenyl-2-(2-pyridylselanyl)ethane - in quantitative yield [18]. 

---