Condensation of beta-hydroxy sulfones and vinyl sulfones with aldehydes and ketones using phenyllithium as base

4 pages Merci à Elsevier pour l'autorisation de déposer cet article sur HAL.Condensation of beta-hydroxysulfones 7a-b with aldehydes and ketones were performed with diverse bases. Phenyllithium proved to be optimum, giving yields of compounds 9-12a-e ranging from 67 to 80%. Condensation of vinyl sulfones 15a-c with aldehydes also worked very well with PhLi, and the resulting adducts 16a-d were transformed into protected syn 1,3-diols flanked with an olefin at the a carbon by a new conjugate addition/elimination sequence. These products are models for the C21-C25 sub-unit of Dolabelides

Synthèse diastéréosélective de diols-1,3 et de triols-1,3,5 à partir de sulfones vinyliques.

Few specific studies have previously been spent building diol-1, 3 syn functionalized α by a double bond. In contrast, the synthesis of triols-1, 3,5 have been many subsequent publications, it appeared Interestingly, before stating our results, to devote the first part methods existing in the literature for the diastereoselective synthesis of these polyols. We then present our general strategy to develop these two types of structures. It involves a common precursor easily accessible, the vinylsulfone I and is shown in the diagram below retrosynthetic cons. Our approach to developing 1,3,5 triols based on Julia coupling type between β-Hydroxy II - so diastereoselective obtained from I - and a carbonyl compound. This approach will be developed during a second part. The third part will be devoted to the construction of 1.3-diols syn functionalized in α by a double bond. These could be obtained after a coupling of I carbonyl compound leading to intermediate IV, by adding a sequence combination / elimination, followed by a reduction of vinyl sulfone. A final section will be devoted to the development of a new method deprotection of ethers triéthylsilyle highlighted in our work.Peu d'études spécifiques ont précédemment été consacrées à la construction de diols-1,3 syn fonctionnalisés en α par une double liaison. En revanche, la synthèse de triols-1,3,5 ayant fait l'objet de nombreuses publications ultérieures, il nous est paru intéressant, avant d'exposer nos résultats, de consacrer une première partie aux méthodes existant dans la littérature pour la synthèse diastéréosélective de ces polyols. Nous présenterons ensuite notre stratégie générale pour élaborer ces deux types de structures. Celle-ci fait intervenir un précurseur commun aisément accessible, la vinylsulfone I et est représentée sur le schéma rétrosynthétique ci-contre. Notre approche pour élaborer des triols 1,3,5 repose sur un couplage de type Julia entre la β-hydroxysulfone II – obtenue de manière diastéréosélective à partir de I – et un composé carbonylé. Cette approche sera développée au cours d'une seconde partie. Notre troisième partie sera consacrée à la construction de diols 1,3-syn fonctionnalisés en α par une double liaison. Ceux-ci pourraient être obtenus, après couplage de I sur un composé carbonylé conduisant à un intermédiaire IV, par une séquence addition conjuguée/élimination, suivie d'une réduction de la sulfone vinylique. Une dernière partie sera consacrée à la mise au point d'une nouvelle méthode de déprotection des éthers de triéthylsilyle mise en évidence au cours de nos travaux

Synthèse diastéréosélective de diols-1,3 et de triols-1,3,5 à partir de vinyl sulfones

PALAISEAU-Polytechnique (914772301) / SudocSudocFranceF

A New, Simple, and Selective Palladium-Catalyzed Cleavage of Triethylsilyl Ethers

International audience(Equation Presented) A simple procedure for the cleavage of triethylsilyl (TES) ethers in the presence of 10 wt % Pd/C in methanol or 95% ethanol is reported. This method allows selective removal of alkyl TES ethers in the presence of aromatic TES ethers or tert-butyldimethylsilyl (TBS) protecting groups

Tandem Conjugate Addition-Elimination for the Diastereoselective Synthesis of 4E-Alkenyl syn 1,3-Diols

4 pagesInternational audienceWe have developed a tandem conjugate addition-elimination sequence for the diastereoselective synthesis of protected allylic syn 1,3-diols, starting from vinyl sulfones. The sulfonyl group was then reduced with sodium amalgam to furnish the E olefin as the major isomer. This method was applied to the synthesis of a trisubstituted alkene modeling the C21-C25 fragment of Dolabelide C

Tandem Conjugate Addition−Elimination for the Diastereoselective Synthesis of 4<i>E</i>-Alkenyl <i>syn</i>-1,3-Diols

We have developed a tandem conjugate addition−elimination sequence for the diastereoselective synthesis of protected allylic syn-1,3-diols, starting from vinyl sulfones. The sulfonyl group was then reduced with sodium amalgam to furnish the E-olefin as the major isomer. This method was applied to the synthesis of a trisubstituted alkene modeling the C21−C25 fragment of Dolabelide C

A New, Simple, and Selective Palladium-Catalyzed Cleavage of Triethylsilyl Ethers

A simple procedure for the cleavage of triethylsilyl (TES) ethers in the presence of 10 wt % Pd/C in methanol or 95% ethanol is reported. This method allows selective removal of alkyl TES ethers in the presence of aromatic TES ethers or tert-butyldimethylsilyl (TBS) protecting groups

Synthesis of functionalized Morita–Baylis–Hillman adducts by a conjugate addition–elimination sequence

We have developed a new conjugate addition–elimination sequence for the diastereoselective synthesis of protected allylic syn 1,3-diols which are Morita–Baylis–Hillman adducts. The synthesis of the substrates involves a challenging cross-metathesis reaction that leads to hindered trisubstituted olefins