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Total Syntheses of (−)‐Grandinolide and (−)‐Sapranthin by the Sharpless Asymmetric Dihydroxylation of Methyl trans ‐3‐Pentenoate: Elucidation of the Stereostructure of (−)‐Sapranthin
Author(s) -
Harcken Christian,
Brückner Reinhard,
Rank Elisabeth
Publication year - 1998
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/(sici)1521-3765(19981102)4:11<2342::aid-chem2342>3.0.co;2-q
Subject(s) - dihydroxylation , sharpless asymmetric dihydroxylation , lactone , alkylation , chemistry , stereochemistry , deprotonation , enantioselective synthesis , organic chemistry , catalysis , ion
The commercially available title ester ( 1 ) was converted into the phytochemicals (−)‐grandinolide ( 3 ) and (−)‐sapranthin ( 4 ) through trans ‐selective alkylations of the “dianions” derived from enantio‐enriched β ‐hydroxy‐ γ ‐lactones and excess LDA. Lactone 2 was obtained from 1 through an asymmetric dihydroxylation (1 step, 78 % ee ). Through alkylation, the “dianion” of 2 gave 3 . The OH group of lactone 2 was also inverted. Deprotonation of the new lactone with excess LDA and alkylation led to 4 whose stereoformula was thereby revised and completed.