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Regio‐ and Stereoselective Synthesis of Bicyclic Limonene‐Based Chiral Aminodiols and Spirooxazolidines
Author(s) -
Le Tam Minh,
Csámpai Antal,
Fülöp Ferenc,
Szakonyi Zsolt
Publication year - 2018
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.201802484
Subject(s) - chemistry , bicyclic molecule , diethylzinc , iminium , stereoselectivity , substituent , ring (chemistry) , benzaldehyde , ketone , cyclopentadiene , organic chemistry , medicinal chemistry , stereochemistry , catalysis , enantioselective synthesis
A library of monoterpene‐based aminodiols was synthesized and applied as chiral catalysts in the addition of diethylzinc to benzaldehyde. The reduction of a bicyclic α‐methylene ketone, derived from natural (−)‐limonene followed by epoxidation, gave the key epoxy alcohol intermediate. Ring opening of the oxirane ring with primary amines induced by lithium perchlorate afforded the required aminodiols. Substituent‐dependent ring closure of the secondary aminodiols with formaldehyde resulted in both spirooxazolidines and a fused 1,3‐oxazine. Cyclization reactions of the studied aminodiols, resulting in spirocyclic oxazolidines and an isomeric perhydro‐1,3‐oxazine‐fused compound along with the possible iminium intermediates, were analyzed by a systematic series of comparative DFT models performed at the B3LYP/6‐31+G(d,p) level of theory.