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Synthesis of the BCD‐Ring Substructure of Granaticin A
Author(s) -
Bachmann Janina,
Mang Christian,
Haustedt Lars Ole,
Harms Klaus,
Koert Ulrich
Publication year - 2012
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.201201104
Subject(s) - chemistry , ketone , dihydroxylation , ring (chemistry) , naphthoquinone , stereochemistry , moiety , acetal , sharpless asymmetric dihydroxylation , lactone , total synthesis , organic chemistry , enantioselective synthesis , catalysis
The BCD‐ring substructure of granaticin A was synthesised following a new approach for the construction of the naphthoquinone moiety. The 2‐oxabicyclo[2.2.2]oct‐5‐ene substructure was accessible stereoselectively using a Sharpless asymmetric dihydroxylation and a diastereoselective ketone reduction in combination with Yoshii's route. The naphthoquinone B‐ring was prepared by addition of an aryllithium intermediate to an anhydride followed by a Friedel–Crafts cyclisation mediated by AlCl 3 and Mg(OTf) 2 . The success of the Friedel–Crafts cyclisation relied on the conversion of the ketone‐carboxylic acid into a lactone acetal.