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Introducing Catalytic Lossen Rearrangements: Sustainable Access to Carbamates and Amines
Author(s) -
Kreye Oliver,
Wald Sarah,
Meier Michael A. R.
Publication year - 2013
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.201200760
Subject(s) - chemistry , catalysis , hydroxamic acid , organic chemistry , methanol , triethylamine , dabco , amine gas treating , reagent , medicinal chemistry
A new, highly efficient and environmentally benign catalytic variant of the Lossen rearrangement is described. Dimethyl carbonate (DMC) as green activation reagent of hydroxamic acids in presence of catalytic amounts of tertiary amine bases {1,5,7‐triazabicyclo[4.4.0]dec‐5‐ene (TBD), 1,8‐biazabicyclo 5.4.0 undec‐7‐ene (DBU), 1,4‐diazabicyclo[2.2.2]octane (DABCO), and triethylamine} and small quantities of methanol initiate the rearrangement. Methyl carbamates were obtained in good to moderate yields when aliphatic hydroxamic acids were employed in this catalytic Lossen rearrangement; under the same conditions aromatic hydroxamic acids yielded anilines. Notably, the mixture of DMC/methanol was recycled several times without observing decreased yields, thus minimizing the produced waste. Moreover, several other organic carbonates were successfully employed in the introduced catalytic Lossen rearrangement procedure.