Phenyl phenylseleno methyl

However, 1-hydroxy-l-phenyl-9-decene-3,5-dione (19), upon selenium-mediated cyclization, affords (L, L )-2-phenyl-8-[(phenylseleno)methyl]-l,7-dixoaspiro[5.5]undecan-4-one (20) in 50% yield with total asymmetric induction. Subsequent Raney nickel reduction gives (E.JS J-S-methyl-2-phenyl-l,7-dioxaspiro[5.5]undecan-4-one (21) in 94% yield 105-106. 

Phenyl phenylselenomethyl tellurium and lithium diisopropylamide in tetrahydrofuran at —78" produced phenyl phenylseleno(lithio)methyl tellurium. This compound reacted with methyl iodide to give phenyl 1-phenylseleno-1-ethyl tellurium. Butyl lithium cleaved... 

Phenylseleno- and methylseleno-alkyllithiums usually exhibit a closely related reactivity towards carbonyl compounds whether the reaction is performed in THF or in ether. As expected, the nudeophilicity of such species often decreases by increasing the substitution around the ct anionic center (6 and 8 Scheme 112), but interestingly they are often far more nucleophilic than the corresponding alkyl-lithiums. However, in some rare cases employing particularly hindered reaction partners there is a significant difference of reactivity between phenyl- and methyl-selenoalkyllithiums when the reactions are performed in THF, since the former reagents are much less nucleophilic than the latter (compare 11 and 12 in Scheme 113 and 17a-17f in Scheme 114). As general trends, a-methylselenoalkyllithiums are more nucleophilic in ether than in THF (compare 15 in Scheme 113.17d and 17e in Scheme 114 and 24 in Scheme 116). 

The use of benzeneseleninic anhydride in the conversion of thiocarbonyl compounds into the corresponding oxo-derivatives has been reported in full similar reactions were achieved using diaryl telluroxides. ° Steroidal ketones reacted with tris(phenylseleno)borane or tris(methylseleno)borane to give phenyl or methyl selenoacetals. 

AMIDES Bis(o-nitrophenyl)phenyl-phosphonate. N,N-Bis(2-oxo-3-oxazoli-dinyl)phosphordiainidic chloride. 2-Chloro-2-oxo-l,3,2-bcnzodioxa-ph05-phole. Iodine azide. N-Methyl-N-phenyl-benzohydrazonyl bromide. Phase-transfer catalysts. N-Phenylseleno-phthalimidc. (SEProlinol. 

Diphenyl-(2-methyl-propyloxy)- E2, 212 Diphenyl-(2-pyridylamino)- E2. 287 Diphenyl-methyl- -trimcthylsilylimid 118 Diplienyl-(2-phenyl-ethi yl)- E2, 48 Diphenyl-phenylseleno- E2, 92 Diphenyl-1-propinyl- E2, 101 Diphenyl- 1-propinyl- -tosylimid E2, 101 Diphenyl-trichlor- E2, 290, 291 Diphenyl-trifluoracetoxy- E2, 19 Diphenyl-trifluoraeetyl- E2, 42 Diphenyl-(2,2,2-trifluor-ethoxy)- E2, 866 Diphenyl-(trifluor-vinyl)- E2, 99... 

The intermediate in this reaction could be either the prostereogenic enolate or the chiral enamine formed in situ. In an attempt to distinguish between these pathways, the chiral enamine prepared from methyl (S)-prolinate was allowed to react with methyl A-phenylseleno-(S)-prolinate. The isolated 2-phenyl-2-phenylselenopropanal had the same enantiomeric excess as that obtained in the direct a-selenenylation of racemic 2-phenylpropanal. This result clearly indicates that the intermediacy of the chiral enamine cannot be excluded7. 

The presence of a group able to delocalize the charge from the caibanionic center favors the synthesis of the carbanion whatever the method used, whereas substitution of the carbanionic center by alkyl groups disfavors it. Thus, whereas methyl phenyl and dimethyl selenide cannot be metallated wiA LDA at -78 °C or 0 C, phenylseleno and methylseleno acetates and propionates lead, on reaction with the same base at -78 °C, to the corresponding organometallics (Scheme 10). - ... 

In general, the elimination rection is easier (i) with arylseleno derivatives bearing an electron-withdrawing group at the ortho or para position of the phenyl ring than with their phenylseleno or methyl-seleno analogs and (ii) when it provides a relatively more-substituted carbon-carbon double bond. 

The reaction involving dichlorocarbene also provides a wide range of epoxides, " including terminal. a.a- and a,p-dialkyl-substituted and tiialkyl-substituted compounds, from a large variety of 3-hy-drcxyalkyl methyl and phenyl selenides (Scheme 162, d). The thallous ethoxide reaction, although it takes place more slowly (especially with phenylseleno derivatives) than under phase transfer catalysis condirions, " has to be in several instances preferred since it avoids the concomitant formation of... 

Under photoirradiation conditions 2-(phenylseleno)propanedioates add to a variety of olefins and acetylenes regioselectively in good yields via phenylseleno group transfer [121]. The group transfer addition of methyl(phenylseleno)malononitrile to a variety of alkenes has been investigated in detail as depicted in Scheme 15.46 group transfer addition to phenyl 1-propenyl sulfide proceeds with high anti selectivity [122]. 

Cyclopropanation. 2-Triethylsilylvinyl phenyl selenide behaves as a (2-phenylseleno-2-triethylsilyl)ethylidenating agent for conjugated double bonds in the presence of Znl2- Chiral adducts are obtained from reaction of di-(—)-menthyl methyl-enemalonate. 

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