Stereoselective Pd-catalyzed etherification and asymmetric synthesis of furanomycin and its analogues from a chiral aziridine.

A chiral aziridine was utilized for the synthesis of the anti-bacterial natural amino acid L-(+)-furanomycin, and its analogues including 5'-epi-furanomycin and norfuranomycin. Key steps of this synthesis are the stereoselective Pd-catalyzed etherification for diallyl ethers and ring closing metathesis.

Nucleophile-dependent regio- and stereoselective ring opening of 1-azoniabicyclo[3.1.0]hexane tosylate.

1-[(1R)-(1-Phenylethyl)]-1-azoniabicyclo[3.1.0]hexane tosylate was generated as a stable bicyclic aziridinium salt from the corresponding 2-(3-hydroxypropyl)aziridine upon reaction with p-toluenesulfonyl anhydride.

CAL-B catalyzed desymmetrization of 3-alkylglutarate: "olefin effect" and asymmetric synthesis of pregabalin.

CAL-B catalyzed desymmetrization of prochiral 3-alkylglutaric acid diesters was performed to prepare optically active 3-alkylglutaric acid monoesters bearing various alkyl substituents, including methyl, ethyl, propyl and allyl groups. Allyl esters showed far better stereoselectivity among the alkyl esters, suggesting possible π-π interactions between the olefin of the substrate and the Trp104 or His224 side chains at the enzyme active site. Based on this reaction, the synthesis of (S)-(+)-3-aminomethyl-5-methylhexanoic acid (pregabalin) was achieved with a 70% overall yield.

Alkylative ring opening of N-methylaziridinium ions and a formal synthesis of tyroscherin.

Alkylative ring-opening reactions of stable 2-substituted N-methylaziridinium ions proceeded with various alkyl- or arylmagnesium bromides in the presence of CuI to yield synthetically valuable and optically pure alkylated acyclic amines in a completely regio- and stereoselective manner. This was applied to a formal synthesis of the cytotoxic natural product tyroscherin.