Lewis acid-promoted direct substitution of 4-methoxy- and 4-phenylthio-2-oxazolidinones by alkyl cuprates. Facile preparation of (3s,4s)-statine and (3s,4s)-cyclohexylstatine.
摘要:
Treatment of 4-methoxy- and 4-phenylthio-2-oxazolidinones with a combination of cuprates and BF3 results in smooth formation of 4-alkyl and 4-aryl derivatives in high yield. By this method, the titled compounds of biological interest are readily synthesized from (4S,5S)-5-allyl-4-methoxy (or 4-phenylthio)-2-oxazolidinones stereoselectively.
The intermediates generated by DIBALH reduction of α-aminoacidesters undergo condensation without racemization with silylketeneacetals and allylstannane in the presence of Lewis acid to afford the corresponding β-hydroxy esters and homoallylic alcohols in good yields while achieving high syn selectivity via an aluminum-assisted chelation control.
promising method for the versatile synthesis of chiral 2-amino alcohols is provided by the enantioselective functionalization of the olefinic moiety of the simple heterocycle, 2-oxazolone, involving a stereodefined introduction of easily replaceable groups followed by stepwise substitution. Versatility of this method is shown in chiral synthesis of unusual hydroxy amino acids such as statine and hydroxyglutamic