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Allenals, divinyl

Acetylation occurs at the 2-position of allene systems (Scheme 8.14). The intermediate 7t-allyl complex breaks down via the nucleophilic displacement of the cobalt carbonyl group by the hydroxide ion to produce the hydroxyketone (7) [ 11 ]. An alternative oxygen-initiated radical decomposition of the complex cannot, however, be totally precluded. The formation of a second major product, the divinyl ketone (8), probably arises from direct interaction of the dicobalt octacarbonyl with the allene and does not require the basic conditions. [Pg.390]

Alkaloids were used as chiral catalysts for the enantioselective prototropic rearrangement of achiral propynyl compounds to chiral allenes with optical purities lower than 1%127. In addition, prototropic rearrangement induced by sodium (-)-mentholate to give the divinylal-lene (M)-l,3,4,6-heptatetraene with op < 1 % is known128. [Pg.562]

Dienes. Uosaturated organic compds of general formula CnH2n-2 containg two double bonds and belonging to the group of polyenes. Typical examples are diolefins, such as allene(propadiene), C3H4 divinyl( 1,3-butadiene), piper ylene( 1,4-pen tad iene),... [Pg.117]

There have been few transformations of vinylcupiate reagents with acid chlorides (Section 1.13.3.1.1). Marino and Linderman have reported a gener preparation of divinyl ketones useful in a Nazarov sense for the formation of cyclopentenones (Scheme 33). Addition of various cuprate species to ethyl propio-late formed a mixed cuprate which is peibaps best represented as the allene (91). In the case of heterocuprates (89) and (90), acylation proceeded in good yield to form the divinyl ketone. Dimethylcuprate afforded none of the desired product but instead produced 1-acetylcyclohexene. The method was generalized for several different acid chlorides. [Pg.431]

Cope rearrangements of allenes incorporated in a large ring together with a double bond afford 2,3-divinylcycloalkenes. e.g.. 13 -> 14, while the cyclic bisallene 15 yields 2.3-divinyl-1,3-cyclo-... [Pg.390]

Ipsenol (3), the pheromone of bark beetles, has been synthesized by conjugate addition of lithium divinyl cuprate to the allenic ketone (I). -... [Pg.100]

Structure-function relationship in the CYP74 family conversion of divinyl ether synthases into allene oxide synthases by site-directed mutagenesis. EEBS Lett 587 2552-2558... [Pg.440]


See other pages where Allenals, divinyl is mentioned: [Pg.117]    [Pg.797]    [Pg.170]    [Pg.18]    [Pg.425]    [Pg.437]    [Pg.203]   
See also in sourсe #XX -- [ Pg.533 ]

See also in sourсe #XX -- [ Pg.533 ]

See also in sourсe #XX -- [ Pg.97 , Pg.533 ]




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