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Catalytic Asymmetric Formal [3+2] Cycloaddition of 2‐Isocyanatomalonate Esters and Unsaturated Imines: Synthesis of Highly Substituted Chiral γ‐Lactams
Author(s) -
Espinosa Miguel,
Blay Gonzalo,
Cardona Luz,
Muñoz M. Carmen,
Pedro José R.
Publication year - 2017
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.201702777
Subject(s) - pyrrolidinones , cycloaddition , electrophile , chemistry , enantiomer , catalysis , enantioselective synthesis , double bond , formal synthesis , conjugate , derivative (finance) , stereochemistry , medicinal chemistry , organic chemistry , mathematical analysis , mathematics , financial economics , economics
Unlike their isocyano and isothiocyanato analogues, isocyanato esters remain almost unexplored as formal 1,3‐dipoles in asymmetric catalytic reactions. The first asymmetric formal [3+2] cycloaddition involving isocyanato esters and electrophilic alkenes is reported. Diisopropyl 2‐isocyanatomalonate reacts with α,β‐unsaturated N ‐( o ‐anisidyl) imines in the presence of a Mg(OTf) 2 –BOX complex to give highly substituted chiral pyrrolidinones featuring a conjugate exocyclic double bond with excellent yields and enantiomeric excesses up to 99 %. Several transformations of the resulting heterocycles, including the synthesis of a pyroglutamic acid derivative, have been carried out.