32466-45-8Relevant articles and documents
Total synthesis of (R,R,R)-α-tocopherol through asymmetric cu-catalyzed 1,4-addition
Termath, Andreas Ole,Sebode, Hanna,Schlundt, Waldemar,Stemmler, René T.,Netscher, Thomas,Bonrath, Werner,Schmalz, Hans-Günther
, p. 12051 - 12055 (2014)
By introducing a disposable activating substituent at C-3, the asymmetric 1,4-addition to a notoriously unreactive 2-substituted chromenone was achieved with high levels of (2R)-stereoselectivity in the presence of a chiral CuI-phosphoramidite
Total Synthesis of α-Tocopherol through Enantioselective Iridium-Catalyzed Fragmentation of a Spiro-Cyclobutanol Intermediate
Ratsch, Friederike,Schlundt, Waldemar,Albat, Dominik,Zimmer, Anne,Neud?rfl, J?rg-Martin,Netscher, Thomas,Schmalz, Hans-Günther
, p. 4941 - 4945 (2019/03/21)
A conceptionally new strategy for the asymmetric (2R-selective) synthesis of α-tocopherol (vitamin E) was developed. In the stereocontrolled key step, a prochiral spiro[chromane-2,3′-cyclobutanol] unit is effectively desymmetrized under C?C bond activation in an unprecedented iridium-catalyzed transformation using (S)-DTBM-SegPhos as a chiral ligand (e.r. 97:3). To complete the synthesis, the side chain was attached through Ru-catalyzed cross-metathesis employing an alkene derived from (R,R)-hexahydrofarnesol. To suppress epimerization during the final hydrogenation, PtO2 had to be used as a catalyst instead of Pd/C. In an alternative approach (employing a propargyl-substituted spiro-cyclobutanol), the side chain was constructed prior to the Ir-catalyzed ring fragmentation (>99:1 d.r.) through enyne cross-metathesis (using an alkene derived from (R)-dihydrocitronellal) followed by Cr-catalyzed 1,4-hydrogenation and (diastereoselective) Pfaltz hydrogenation of the resulting triple-substituted olefin. The work demonstrates the potential of iridium catalysis for enantioselective C?C bond activation.
SYNTHESIS OF CHROMANE COMPOUNDS AND THEIR DERIVATIVES BY A COPPER-CATALYZED CONJUGATE ADDITION REACTION
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, (2015/05/06)
The present invention relates to the preparation of chromane compounds and their derivatives by a copper-catalyzed conjugate addition reaction. It has been observed that in highly stereoselective manner a methyl group can be introduced to the 2 position o