1068600-85-0Relevant academic research and scientific papers
Structure-Elucidating Total Synthesis of the (Polyenoyl)tetramic Acid Militarinone C §
Brückner, Reinhard,Drescher, Christian,Hamburger, Matthias,Keller, Morris,Potterat, Olivier
supporting information, (2020/03/30)
The (polyenoyl)tetramic acid militarinone C (1) heads a family of seven members. Before our work, the configuration of C-5 was unknown whereas the configurations of C-8′ and C-10′ were either (R,R) or (S,S). We synthesized the four stereoisomers of constitution 1, which conform with these insights. This included cross-coupling both enantiomers of the western building block (8) with both enantiomers of the eastern building block (9). The specific rotations of the resulting 1 isomers suggested that natural 1 is configured like the coupling partners (S)-8 and (R,R)-9. This conclusion was corroborated by degrading natural 1 to alcohol 35 and by proving its configurational identity with synthetic (R,R)-35.
Synthetic studies on homophymine A: stereoselective synthesis of (2R,3R,4R,6R)-3-hydroxy-2,4,6-trimethyloctanoic acid
Bellotta, Filomena,D'Auria, Maria Valeria,Sepe, Valentina,Zampella, Angela
experimental part, p. 3659 - 3663 (2009/09/05)
An efficient and highly stereocontrolled synthesis of (2R,3R,4R,6R)-3-hydroxy-2,4,6-trimethyloctanoic acid, the β-hydroxy acid unit that acylates the N-terminus of homophymine A, has been devised starting from iodoethane and (S,S)-pseudoephedrine propionamide in 9 steps and 36% average overall yield. Comparison of the 1H and 13C NMR and optical rotation data of the resulting β-hydroxy acid with the natural fragment unambiguously verifies the configurational assignment as (2R,3R,4R,6R).
Stereocontrolled alkylative construction of quaternary carbon centers
Kummer, David A.,Chain, William J.,Morales, Marvin R.,Quiroga, Olga,Myers, Andrew G.
supporting information; experimental part, p. 13231 - 13233 (2009/02/06)
Protocols for the stereodefined formation of α,α-disubstituted enolates of pseudoephedrine amides are presented followed by the implementation of these in diastereoselective alkylation reactions. Direct alkylation of α,α-disubstituted pseudoephedrine amide substrates is demonstrated to be both efficient and diastereoselective across a range of substrates, as exemplified by alkylation of the diastereomeric pseudoephedrine α-methylbutyramides, where both substrates are found to undergo stereospecific replacement of the α-C-H bond with α-C-alkyl, with retention of stereochemistry. This is shown to arise by sequential stereospecific enolization and alkylation reactions, with the alkyl halide attacking a common π-face of the E- and Z-enolates, proposed to be opposite the pseudoephedrine alkoxide side chain. Pseudoephedrine α-phenylbutyramides are found to undergo highly stereoselective but not stereospecific α-alkylation reactions, which evidence suggests is due to facile enolate isomerization. Also, we show that α,α-disubstituted pseudoephedrine amide enolates can be generated in a highly stereocontrolled fashion by conjugate addition of an alkyllithium reagent to the s-cis-conformer of an α-alkyl-α,β-unsaturated pseudoephedrine amide, providing α,α-disubstituted enolate substrates that undergo alkylation in the same sense as those formed by direct deprotonation. Methods are presented to transform the α-quaternary pseudoephedrine amide products into optically active carboxylic acids, ketones, primary alcohols, and aldehydes. Copyright
Chiral aggregates formed from methylated tetraenoic fatty acids: Formation of both antipodes of chiral aggregates from a single enantiomer and time-dependent stereomutation
Ma, Jianguo,Cheon, Hwan-Sung,Kishi, Yoshito
, p. 319 - 322 (2008/02/03)
(Chemical Equation Presented) Formation and behaviors of chiral aggregates of methylated tetraenoic fatty acids (TE-FAs) were reported. In the C-24 TE-FA series, the aggregate prepared by dispersing an ethanol stock solution of C-24 TE-FA 1b into sodium phosphate buffer gave a strong positive Cotton effect, whereas the aggregate prepared from a methanol stock solution gave a negative Cotton effect. In the C-20 TE-FA series, the aggregate prepared from an ethanol stock solution of C-20 TE-FA 2b exhibited time-dependent chirality inversion.
