22255-47-6Relevant articles and documents
Synthesis of C40-symmetrical fully conjugated carotenoids by olefin metathesis
Fontan, Noelia,Dominguez, Marta,Ulvarez, Rosana,De Lera, Ungel R.
experimental part, p. 6704 - 6712 (2012/01/03)
In an effort to push olefin metathesis to the limits of conjugation in reactants and products, the C40-symmetrical carotenoids β,β-carotene (1), lycopene (2), (3R,3′R)-zeaxanthin (3), and rac-isozeaxanthin (4), which are conjugated undecaenes, have been synthesized from C21-terminal hexaenes by treatment with Grubbs' second-generation Ru catalyst in dichloromethane at 50 °C.
A convenient cross-metathesis approach to trisporins
López-Sánchez, Cristóbal,Hernández-Cervantes, Carmen,Rosales, Antonio,álvarez-Corral, Míriam,Mu?oz-Dorado, Manuel,Rodríguez-García, Ignacio
experimental part, p. 9542 - 9549 (2010/02/27)
Three series of trisporins have been prepared using a strategy in which a cross-metathesis is the key step. This reaction has proved to be highly regioselective, allowing the combination of α- or β-ionone derivatives having a 1,1-disustituted olefin with
Alkylidenation of carbonyl compounds with gem-dizincioalkanes mediated with titanium dichloride
Matsubara, Seijiro,Mizuno, Tsuyoshi,Otake, Tasuyuiki,Kobata, Masami,Utimoto, Kiitiro,Takai, Kazuhiko
, p. 1369 - 1371 (2007/10/03)
Olefination of carbonyl compounds with gem-dizincio-alkanes, bis(iodozincio)methane, 1,1-bis(iodozincio)ethane, and bis(bromozincio)methyltrimethylsilane, afforded the corresponding olefins in good to excellent yields.
Pyrylium salts in polyene natural product synthesis: organometallic additions to 4-methylpyrylium tetrafluoroborate
Taylor, Richard J. K.,Hemming, Karl,Medeiros, Edna Faria De
, p. 2385 - 2392 (2007/10/02)
The synthetic utility of organometallic additions to pyrylium salts as a procedure for the stereocontrolled preparation of 2Z,4E-dienals, and the use of these compounds in polyene natural product synthesis, is summarised.The extension of this methodology to 4-methylpyrylium tetrafluoroborate to give a new route to 3-methyl-2Z,4E-dienals via a six-carbon organometallic homologation procedure is then described.Finally, the utilisation of this methodology to provide a concise synthetic approach to 13Z-retinal, retinal and a range of retinal analogues is then elaborated.
Highly selective synthesis of vitamin A and its derivatives. Critical comparison of some known palladium-catalyzed alkenyl-alkenyl coupling reactions
Negishi,Owczarczyk
, p. 6683 - 6686 (2007/10/02)
Vitamin A has been synthesized cleanly and selectively with essentially complete control of stereo- and regiochemistry in four linear and six overall steps from β-ionone and (E)-3-methyl-2-penten-4-yn-1-ol via Pd-catalyzed cross coupling of an alkenylzinc with an alkenyl iodide; the use of other metals, such as Al, Zr, Mg, B, Cu, and Sn, being inferior to that of Zn.
A ZIRCONIUM-PROMOTED METHYLENATION OF ALDEHYDES, KETONES, AND ENONES
Tour, James M.,Bedworth, Peter V.,Wu, Ruilian
, p. 3927 - 3930 (2007/10/02)
Treatment of zirconocene dichloride with dibromomethane and zinc affords an organometallic intermediate which rapidly methylenates aldehydes, ketones, and enones at room temperature.
A CONVENIENT AND EFFICIENT METALLATION OF METHYLSILANE. CARBONYL METHYLENATIONS USING METALLATED (2-AMINOALKOXY)TRIMETHYLSILANE
Hosomi, Akira,Kohra, Shinya,Tominaga, Yoshinori,Shoji, Masataka,Sakurai, Hideki
, p. 1663 - 1665 (2007/10/02)
When (2-aminoalkoxy)trimethylsilane is activated by two intramolecular heteroatoms (oxygen and nitrogen), it undergoes metallation efficiently with t-butyllithium to yield α-silyl carbanion.This process is applicable to carbonyl methylenations.Keywords-lithiated methylsilane; α-silyl carbanion; (2-aminoalkoxy)trimethylsilane; Peterson reaction; alkene synthesis
