22644-28-6Relevant articles and documents
Synthesis and complete structure determination of a sperm-activating and -attracting factor isolated from the ascidian ascidia sydneiensis
Watanabe, Tomohiro,Shibata, Hajime,Ebine, Makoto,Tsuchikawa, Hiroshi,Matsumori, Nobuaki,Murata, Michio,Yoshida, Manabu,Morisawa, Masaaki,Lin, Shu,Yamauchi, Kosei,Sakai, Ken,Oishi, Tohru
, p. 985 - 997 (2018/05/04)
For the complete structure elucidation of an endogenous sperm-activating and -attracting factor isolated from eggs of the ascidian Ascidia sydneiensis (Assydn-SAAF), its two possible diastereomers with respect to C-25 were synthesized. Starting from ergosterol, the characteristic steroid backbone was constructed by using an intramolecular pinacol coupling reaction and stereoselective reduction of a hydroxy ketone as key steps, and the side chain was introduced by Julia-Kocienski olefination. Comparison of the NMR data of the two diastereomers with those of the natural product led to the elucidation of the absolute configuration as 25S; thus the complete structure was determined and the first synthesis of Assydn-SAAF was achieved.
Iridium-catalyzed asymmetric hydrogenation of racemic α-substituted lactones to chiral diols
Yang, Xiao-Hui,Yue, Hai-Tao,Yu, Na,Li, Yi-Pan,Xie, Jian-Hua,Zhou, Qi-Lin
, p. 1811 - 1814 (2017/03/09)
We report a protocol for the highly efficient iridium-catalyzed asymmetric hydrogenation of racemic α-substituted lactones via dynamic kinetic resolution. Using Ir-SpiroPAP (R)-1d as a catalyst, a wide range of chiral diols were prepared in a high yield (80-95%) with a high enantioselectivity (up to 95% ee) under mild reaction conditions. This protocol was used for enantioselective syntheses of (?)-preclamol and a chiral 2,5-disubstituted tetrahydropyran.
Using heteroaryl-lithium reagents as hydroxycarbonyl anion equivalents in conjugate addition reactions with (S, S)-(+)-pseudoephedrine as chiral auxiliary; Enantioselective synthesis of 3-substituted pyrrolidines
Alonso, Beatriz,Ocejo, Marta,Carrillo, Luisa,Vicario, Jose L.,Reyes, Efraim,Uria, Uxue
, p. 614 - 627 (2013/03/13)
We have developed an efficient protocol for carrying out the stereocontrolled formal conjugate addition of hydroxycarbonyl anion equivalents to α,β-unsaturated carboxylic acid derivatives using (S,S)-(+)-pseudoephedrine as chiral auxiliary, making use of the synthetic equivalence between the heteroaryl moieties and the carboxylate group. This protocol has been applied as key step in the enantioselective synthesis of 3-substituted pyrrolidines in which, after removing the chiral auxiliary, the heteroaryl moiety is converted into a carboxylate group followed by reduction and double nucleophilic displacement. Alternatively, the access to the same type of heterocyclic scaffold but with opposite absolute configuration has also been accomplished by making use of the regio- and diastereoselective conjugate addition of organolithium reagents to α,β,γ,δ-unsaturated amides derived from the same chiral auxiliary followed by chiral auxiliary removal, ozonolysis, and reductive amination/intramolecular nucleophilic displacement sequence.