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Ozonolyses of Enantiopure 4‐Alkoxy‐3,6‐dihydro‐2 H ‐1,2‐oxazines:An Expedient Route to Functionalized α‐Amino‐β‐hydroxy Esters
Author(s) -
Helms Matthias,
Reißig HansUlrich
Publication year - 2005
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.200400734
Subject(s) - enantiopure drug , chemistry , oxazines , alkoxy group , ozonolysis , acylation , organic chemistry , stereochemistry , catalysis , enantioselective synthesis , alkyl
Abstract Ozonolysis and subsequent in situ acylation/base treatment converted the enantiopure carbohydrate‐derived 1,2‐oxaz‐ines 1 , 5 , 8 (either syn ‐ or anti ‐configured) and anti ‐ 11 into the highly functionalized α‐amino‐β‐hydroxy esters 2 , 6 , 9 and 12 in moderate to good yields. Ketals of 5‐hydroxylated 1,2‐oxazines (e.g., syn ‐ 3 ) were formed as side products in most cases; the reactions of precursors syn ‐ and anti ‐ 8 even provided the ketals syn ‐ or anti ‐ 10 as major components. The synthesized functionalized amino esters are valuable intermediates, as demonstrated by the subsequent transformation of anti ‐ 2 into the enantiopure building blocks 13 – 15 . Since precursor 1,2‐oxazines were prepared via lithiated alkoxyallenes, the latter species were serving as formyl ester anion equivalents. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)