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Enantioselective Preparation of (2 R )‐ and (2 S )‐Azetidine‐2‐carboxylic Acids
Author(s) -
Wessig Pablo,
Schwarz Jutta
Publication year - 1998
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/(sici)1522-2675(19981007)81:10<1803::aid-hlca1803>3.0.co;2-4
Subject(s) - chemistry , azetidine , stereoselectivity , enantioselective synthesis , amino acid , bond cleavage , serine , stereochemistry , cleavage (geology) , diol , organic chemistry , catalysis , enzyme , biochemistry , geotechnical engineering , fracture (geology) , engineering
The enantiomerically pure amino ketones 13 and 31 were prepared starting from the commercially available amino diol 9 and D ‐serine ( 21 ), respectively. Irradiation afforded highly functionalized azetidinols 15 and 33 in a fully stereoselective manner and in high yields, whereas N ‐phenacylglycine 5 gave only the secondary products of a Norrish‐Type‐II cleavage. Compounds 15 and 33 were converted into (2 R )‐ and (2 S )‐azetidine‐2‐carboxylic acids 20 and 37 , respectively, in several steps. The influence of H‐bonds on efficiency, chemo‐, and stereoselectivity of the photochemical cyclization of 5 , 13 , and 31 was discussed. It was shown that conformational analysis of corresponding triplet biradicals is often valuable in understanding the photochemistry of amino ketones.