Day: September 15, 2022

Cichowicz, Nathan R.;Kaplan, Will;Khomutnyk, Yaroslav;Bhattarai, Bijay;Sun, Zhankui;Nagorny, Pavel published 《Concise Enantioselective Synthesis of Oxygenated Steroids via Sequential Copper(II)-Catalyzed Michael Addition/Intramolecular Aldol Cyclization Reactions》 in 2015. The article was appeared in 《Journal of the American Chemical Society》. They have made some progress in their research.Application In Synthesis of (4R,4’R)-2,2′-Cyclopropylidenebis(4,5-dihydro-4-phenyloxazole) The article mentions the following:

A new scalable enantioselective approach to functionalized oxygenated steroids is described. This strategy is based on chiral bis(oxazoline) copper(II) complex-catalyzed enantioselective and diastereoselective Michael reactions of cyclic ketoesters and enones to install vicinal quaternary and tertiary stereocenters. In addition, the utility of copper(II) salts as highly active catalysts for the Michael reactions of traditionally unreactive β,β’-enones and substituted β,β’-ketoesters that results in unprecedented Michael adducts containing vicinal all-carbon quaternary centers is also demonstrated. The Michael adducts subsequently undergo base-promoted diastereoselective aldol cascade reactions resulting in the natural or unnatural steroid skeletons. The exptl. and computational studies suggest that the torsional strain effects arising from the presence of the Δ⁵-unsaturation are key controlling elements for the formation of the natural cardenolide scaffold. The described method enables expedient generation of polycyclic mols. including modified steroidal scaffolds as well as challenging-to-synthesize Hajos-Parrish and Wieland-Miescher ketones. To complete the study, the researchers used (4R,4’R)-2,2′-Cyclopropylidenebis(4,5-dihydro-4-phenyloxazole) (cas: 1819994-24-5) .

Oxazolidines are weaker bases (pKa 6–7) than parent β-amino alcohols and found to be more lipophilic than the parent compound at physiological pH.Application In Synthesis of (4R,4’R)-2,2′-Cyclopropylidenebis(4,5-dihydro-4-phenyloxazole) For example, the oxazolidine prodrug of phenylephrine prepared from pivaldehyde has penetrated the cornea much more easily than the parent drug as a result of increased lipophilicity.

Reference:
Oxazolidine – Wikipedia,
Oxazolidine | C3H7NO – PubChem

HPLC of Formula: 1819994-24-5In 2018, Bhattarai, Bijay;Nagorny, Pavel published 《Enantioselective Total Synthesis of Cannogenol-3-O-α-L-rhamnoside via Sequential Cu(II)-Catalyzed Michael Addition/Intramolecular Aldol Cyclization Reactions》. 《Organic Letters》published the findings. The article contains the following contents:

A concise and scalable enantioselective total synthesis of the natural cardenolides cannogenol and cannogenol-3-O-α-L-rhamnoside has been achieved in 18 linear steps. The synthesis features a Cu(II)-catalyzed enantioselective and diastereoselective Michael reaction/tandem aldol cyclization and a one-pot reduction/transposition, which resulted in a rapid (6 linear steps) assembly of a functionalized intermediate containing C19 oxygenation that could be elaborated to cardenolide cannogenol. In addition, a strategy for achieving regio- and stereoselective glycosylation at the C3 position of synthetic cannogenol was developed and applied to the preparation of cannogenol-3-O-α-L-rhamnoside. And (4R,4’R)-2,2′-Cyclopropylidenebis(4,5-dihydro-4-phenyloxazole) (cas: 1819994-24-5) was used in the research process.

Oxazolidines are weaker bases (pKa 6–7) than parent β-amino alcohols and found to be more lipophilic than the parent compound at physiological pH.HPLC of Formula: 1819994-24-5 For example, the oxazolidine prodrug of phenylephrine prepared from pivaldehyde has penetrated the cornea much more easily than the parent drug as a result of increased lipophilicity.

Reference:
Oxazolidine – Wikipedia,
Oxazolidine | C3H7NO – PubChem