89656-82-6Relevant academic research and scientific papers
Total Synthesis of -Mitrephorone A
Richter, Matthieu J. R.,Schneider, Michael,Brandst?tter, Marco,Krautwald, Simon,Carreira, Erick M.
supporting information, p. 16704 - 16710 (2018/12/14)
The first synthesis of mitrephorone A is disclosed along with discussion and study of synthetic strategies. The natural product includes a highly congested hexacyclic ent-trachylobane diterpenoid framework featuring a rare, embedded oxetane. The synthetic analysis presented dissects a number of approaches for the synthesis of the central oxetane, including carbonyl-olefin photocycloadditions, Prins-type cyclizations, and oxidative ring closures. In the successful route, three [4 + 2] cycloadditions enable rapid construction of all carbocycles. A novel late-stage oxidative cyclization of a hydroxy diosphenol with Koser's reagent furnishes the pivotal oxetane moiety.
Michael reaction of acyclic β-enaminoesters derived from α-alkyl-β-ketoesters and chiral α-methylbenzylamine: Stereoselective generation of quaternary carbon centres
Maiti,Ghoshal,Mukhopadhyay,Achari,Banerjee
, p. 1072 - 1080 (2007/10/03)
Michael reaction of electrophilic olefins with acyclic β-enaminoester substrates derived from α-substituted β-ketoesters and (R)- or (S)-α-methylbenzylamine under neutral conditions resulted in the enantioselective formation of quaternary centres. The add
PREPARATION OF OPTICALLY ACTIVE TRICYCLIC 1,4-DIOXEPIN-5-ONE DERIVATIVES AND ITS APPLICATION TO ASYMMETRIC ALKYLATION
Kato, Keisuke,Suemune, Hiroshi,Sakai, Kiyoshi
, p. 413 - 424 (2007/10/02)
Chiral bicyclic α,β-unsaturated lactones (6a,b and 8a,b) were easily synthesized from chiral cyclic diols (2-4) and cyclic β-keto esters (1a,b).Alkylation of 8b proceeded in a highly diastereoselective manner to afford a quaternary carbon.
Asymmetric Alkylation Using Chiral Cyclic Diols to Prepare a Quaternary Carbon
Kato, Keisuke,Suemune, Hiroshi,Sakai, Kiyoshi
, p. 3315 - 3326 (2007/10/02)
Asymmetric alkylation of cyclic and acyclic β-keto ester acetals (4, 5, 13, 14, and 18) with C2-symmetric cycloalkane-1,2-dioxy moiety proceeded in a highly diastereoselective manner to afford enol ethers (9-12, 15-17, 19a-c) with a chiral quat
Stereoselective reactions. XXI. Asymmetric alkylation of α-alkyl β-keto esters to α,α-dialkyl β-keto esters having either (R)- Or (S)-chiral quaternary center depending on the solvent system
Ando, Kaori,Takemasa, Yataka,Tomioka, Kiyoshi,Koga, Kenji
, p. 1579 - 1588 (2007/10/02)
Asymmetric alkylation reaction of chiral enamines prepared from α-alkyl β-keto esters and (S)-valine tert-butyl ester leading to either enantiomer is described. Lithiated chiral enamines can be alkylated with alkyl halides in a toluene solvent in the presence of HMPA to give, after hydrolysis, α,α-dialkyl β-keto esters in 70-99%ee. The reactions in the presence of THF, dioxolane, or trimethylamine, instead of HMPA, afford the corresponding antipodes with enantiomeric purities of 44-92%ee. The present method provides a procedure for the synthesis of both enantiomers of α,α-dialkyl β-keto esters in high enantiomeric purities starting from the same chiral enamines.
FACTORS CONTROLLING THE DIASTEREOFACE SELECTIVITY IN THE COMPLEMENTARY ASYMMETRIC ALKYLATION OF α-ALKYL β-KETO ESTERS
Tomioka, Kiyoshi,Ando, Kaori,Takemasa, Yutaka,Koga, Kenji
, p. 5677 - 5680 (2007/10/02)
Complementary asymmetric alkylation reaction of the lithioenamine derived from 2-methoxycarbonylcyclohexanone and (S)-valine tert-butyl ester was examined by employing the various electron pair donating additives in a toluene solvent, in order to clarify
