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Vicinal dialkylation electrophiles

The general reaction sequence has been named more specifically as tandem vicinal dialkylation, nucleophilic-electrophilic carbacondensation,11 dicarbacondensation1213 or conjugate addition-enolate trapping,14 usually in reference to the fact that most of the reaction examples available create two new vicinal carbon-carbon bonds. Many noncarbon nucleophiles and electrophiles also are known, resulting... [Pg.238]

Esters are far less reactive as electrophiles when compared to aldehydes and ketones. Successful tandem vicinal dialkylations are possible using alkyl formates,67 but most esters lack the needed reactivity. More reactive thioesters can serve as electrophiles in these sequences.208 Presence of a potentially electrophilic ester group as a substituent in the conjugate enolate permits very efficient Dieckmann cycliza-tion to take place as the second step of a MIRC sequence (e.g. equations 5118 and 52).24 Ortho esters are far more reactive, giving p-keto esters as adducts when used in sequences that employ enones as substrates.230... [Pg.261]

Michael addition.1 This ketene silyl acetal undergoes Michael addition to a,fl-enones in acetonitrile in the absence of a Lewis acid to afford the corresponding O-silylated Michael adduct in high yield. These O-silyl enolates undergo site-specific electrophilic substitution. This sequence was used for vicinal dialkylation of cyclohexanone (equation I) and of cyclopentanone. It is particularly useful for synthesis of methyl jasmonate and related compounds from cyclopentenone. [Pg.482]


See other pages where Vicinal dialkylation electrophiles is mentioned: [Pg.251]    [Pg.252]    [Pg.254]    [Pg.256]    [Pg.389]    [Pg.252]    [Pg.260]   
See also in sourсe #XX -- [ Pg.4 , Pg.259 ]

See also in sourсe #XX -- [ Pg.4 , Pg.259 ]




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Vicinal dialkylation

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