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A Practical Route to Regiospecifically Substituted ( R )‐ and ( S )‐Oxazolylphenols
Author(s) -
Scheurer Andreas,
Mosset Paul,
Bauer Walter,
Saalfrank Rolf W.
Publication year - 2001
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 - 10.1002/1099-0690(200108)2001:16<3067::aid-ejoc3067>3.0.co;2-0
Subject(s) - chemistry , steric effects , alcohol , salicylic acid , nitro , stereochemistry , serine , amino acid , organic chemistry , medicinal chemistry , enzyme , biochemistry , alkyl
New, diversely substituted phenolic oxazolines 14a − d and 15a − d were prepared by two complementary routes A and B, starting from salicylic derivatives 4 − 7 and various enantiomerically pure 1,2‐amino alcohols 13a − d . In route A, the 1,2‐amino alcohols 13a − d were directly condensed with the salicylic acids 5 and 7 , using the Appel reaction, whereas in route B the amino alcohols 13b − d were treated with the 2‐hydroxybenzonitriles 4 and 6 , under Witte−Seeliger conditions. The latter route was advantageous for L ‐valinol 13b and L ‐ tert ‐leucinol 13c , while route A was the method of choice for the new, sterically demanding amino alcohol 13a , prepared from D ‐ and L ‐serine. The nitro group in the salicylic derivatives 5 and 6 was introduced by means of a regiospecific ipso substitution of a tert ‐butyl group by nitric acid. The structure of the nitro product 5 was unambiguously assigned by NOE spectroscopy on the basis of the recently developed DPFGSE‐ROE pulse sequence.