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Aza‐Quaternary Scaffolds from Selective Bond Cleavage of Bridgehead‐Substituted 7‐Azabicyclo[2.2.1]heptane: Total Synthesis of (+)‐Cylindricines C–E and (−)‐Lepadiformine A
Author(s) -
Pandey Ganesh,
Janakiram Vaitla
Publication year - 2015
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/chem.201501859
Subject(s) - desymmetrization , bicyclic molecule , aldol reaction , bond cleavage , total synthesis , stereochemistry , chemistry , enantiomer , enantioselective synthesis , heptane , octene , ring strain , cleavage (geology) , combinatorial chemistry , ring (chemistry) , catalysis , organic chemistry , materials science , ethylene , fracture (geology) , composite material
A novel bridgehead‐substituted aza‐bicyclic framework has been designed and developed in both enantiomeric forms through an asymmetric desymmetrization reaction. Strategic exploitation of the ring strain in the aza‐bicyclic framework has been utilized for the construction of the chiral aza‐quaterenary scaffolds by selective bond fragmentation processes. Furthermore, a strategically designed precursor is employed for selective bond cleavage to initiate a cascade rearrangement for the total synthesis of the 1‐azaspirotricyclic marine alkaloids (+)‐cylindricines C, D, and E, as well as (−)‐lepadiformine A. An oxidation/retro‐aldol/aza‐Michael sequence generated three new chiral centers with the required configuration in one pot.