Conjugate addition of Me3SiMe2SiLi to cycloalk-2-en-1-ones, ketalization, Tamao-Fleming oxidation (Bu4NF, then H2O2, KHCO3), TPAP oxidation and acid hydrolysis generates 2-methyl cycloalkane-1,3-diones. Ketalization is needed in order to prevent addition of Me3Si(-) to the carbonyl. The pentamethyldisilanyl group has advantages over other silicon units that are used in Tamao-Fleming procedures.
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http://dx.doi.org/10.1039/c5ob02402a | DOI Listing |
Nature
November 2023
Institut für Chemie, Technische Universität Berlin, Berlin, Germany.
'Organic silicon' is not found in nature but modern chemistry is hard to imagine without silicon bound to carbon. Although silicon-containing commodity chemicals such as those emerging from the 'direct process' look simple, it is not trivial to selectively prepare aryl-substituted and alkyl-substituted (functionalized) silicon compounds, known as silanes. Chlorosilanes such as MeSiCl (n = 1-3) as well as SiCl (n = 4) are common starting points for the synthesis of silicon-containing molecules.
View Article and Find Full Text PDFAntibiotics derived from the diterpene fungal metabolite (+)-pleuromutilin (1) are useful agents for the treatment Gram-positive infections in humans and farm animals. Pleuromutilins elicit slow rates of resistance development and minimal cross-resistance with existing antibiotics. Despite efforts aimed at producing new derivatives by semisynthesis, modification of the tricyclic core is underexplored, in part due to a limited number of functional group handles.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
May 2017
Max-Planck-Institut für Kohlenforschung, 45470, Mülheim/Ruhr, Germany.
Treatment of alkenylstannanes with Cu(OAc) /Et N affords the corresponding enol esters or ketones under conditions that proved compatible with many common functionalities; these include groups that would neither survive under the standard Tamao-Fleming conditions for the oxidation of Csp2 -SiR bonds nor under the conditions commonly used to oxidize C-B bonds. Chiral centers adjacent to the unveiled carbonyls are not racemized and competing protodestannation is marginal, even if the substrate carries unprotected -OH groups as internal proton sources. Therefore, the procedure is well suited for the preparation of acyloin and aldol derivatives.
View Article and Find Full Text PDFOrg Biomol Chem
February 2016
Chemistry Department, University of Alberta, Edmonton, Alberta T6G 2G2, Canada.
Conjugate addition of Me3SiMe2SiLi to cycloalk-2-en-1-ones, ketalization, Tamao-Fleming oxidation (Bu4NF, then H2O2, KHCO3), TPAP oxidation and acid hydrolysis generates 2-methyl cycloalkane-1,3-diones. Ketalization is needed in order to prevent addition of Me3Si(-) to the carbonyl. The pentamethyldisilanyl group has advantages over other silicon units that are used in Tamao-Fleming procedures.
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