The reduction of N-protected amino ketones can be carried stereoselectively to produce either the syn- or anti-amino alcohol diastereomer. Carbamate-protected amino ketones can be reduced predictably and selectively to anti-amino alcohols with LiAlH(O-t-Bu)3 in ethanol at -78 degrees C. N-Trityl-protected amino ketones can be reduced selectively to syn-amino alcohols with LiAlH(O-t-Bu)3 in THF at -5 degrees C.
A simple and efficient method for the synthesis of anti-N-protected amino epoxides from carbamate-protected amino acids is described. The two key steps are the monobromination of a beta-ketoester and chelation-controlled reduction of a bromomethyl ketone intermediate. Good overall yields, high diastereoselectivity, and excellent functional group compatibility are characteristic.
A nine-step (!) solid-phase synthesis and subsequent cleavage with cyclization from the polymeric support were the keys to preparing high-quality molecular libraries of thiazolylhydantoines 1 from modified amino acid building blocks. Each step in the synthesis is different. Because the final cyclization cleaves only molecules that have been successfully constructed, the products obtained are pure. R , R =alkyl; R =aryl, arylO; R =allyl.
The successful application of the Amdt-Eistrrt protocol starting from commercially available N-{ [(93i-fluoren-9-yl)methoxy]carbonyl}-protected (Fmoc) cc-amino acids leading to enantiomerically pure N-Fmoc-protected p-amino acids in only two steps and with high yield is reported.
amino alcoholsamino alcohols (acyclic compounds) P 0130
-077Highly Stereoselective Syntheses of syn-and anti-1,2-Amino Alcohols.-Stereoselective reductions of N-protected amino ketones to furnish either the anti-or syn-amino alcohol are investigated. The results are discussed based on chelation vs. Felkin-Anh control [treatment of (IIId) with LiAlH(OtBu) 3 affords a mixture of ketone and ester reduction products]. -(HOFFMAN, ROBERT V.; MASLOUH, NAJIB; CERVANTES-LEE, FRANCISCO; J. Org.
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