116996-56-6Relevant articles and documents
Structures and Reactivities of Sodiated Evans Enolates: Role of Solvation and Mixed Aggregation on the Stereochemistry and Mechanism of Alkylations
Zhang, Zirong,Collum, David B.
, p. 388 - 401 (2019)
Oxazolidinone-based sodiated enolates (Evans enolates) were generated using sodium diisopropylamide (NaDA) or sodium hexamethyldisilazide (NaHMDS) in the presence of N,N,N′,N′-tetramethylethylenediamine (TMEDA), (R,R)-trans-N,N,N′,N′-tetramethylcyclohexanediamine [(R,R)-TMCDA], or (S,S)-TMCDA. 13C NMR spectroscopic analysis in conjunction with the method of continuous variations (MCV), x-ray crystallography, and density functional theory (DFT) computations revealed the enolates to be octahedral bis-diamine-chelated monomers. Rate and computational studies of an alkylation with allyl bromide implicate a bis-diamine-chelated-monomer-based transition structure. The sodiated Evans enolates form mixed dimers with NaHMDS, NaDA, or sodium 2,6-di-tert-butylphenolate, the reactivities of which are examined. Stereoselective quaternizations, aldol additions, and azaaldol additions are described.
Synthesis of side-chain oxysterols and their enantiomers through cross-metathesis reactions of Δ22 steroids
Brownholland, David P.,Covey, Douglas F.
, p. 22 - 31 (2017)
A synthetic route that utilizes a cross-metathesis reaction with Δ22 steroids has been developed to prepare sterols with varying C-27 side-chains. Natural sterols containing hydroxyl groups at the 25 and (25R)-26 positions were prepared. Enantiomers of cholesterol and (3β,25R)-26-hydroxycholesterol (27-hydroxycholesterol) trideuterated at C-19 were prepared for future biological studies.
Enantioselective Synthesis of the Proposed Structure of Santinol D
Xiong, Xin,Wu, Yikang,Liu, Bo
, p. 948 - 960 (2020/02/15)
In connection with structural verification of santinol D, a unique tricylglycerol isolated from Helichrysum italicum subsp. microphyllum, four possible isomers of its C-2'''and C-4''' centers were synthesized. The two enolizable chiral centers were installed with pre-defined absolute configurations using Evans alkylation and aldol condensation, respectively. The extra chiral center introduced in the aldol condensation was removed by Dess–Martin oxidation to convert the adjacent methine group into the highly enolizable subunit of an α-alkyl-β-keto ester at the end of the synthesis. The synthetic isomers provided unequivocal physical and NMR data for every single enantiomer and thus provided the information required for the configurational assignment of this natural product. With the aid of a model compound, the racemization of such species was examined polarimetrically under several sets of typical conditions and the rates were also calculated from the corresponding kinetics data.
SUBSTITUTED PYRAZOLOAZEPIN-8-ONES AND THEIR USE AS PHOSPHODIESTERASE INHIBITORS
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Page/Page column 42; 43, (2018/07/05)
The present invention relates to novel pyrazoloazepin-8-ones with phosphodiesterase inhibitory activity, as well as to their use as therapeutic agents in the treatment of inflammatory diseases and conditions.
