Base catalyzed sustainable synthesis of phenyl esters from carboxylic acids using diphenyl carbonate
Phenyl esters were obtained in moderate to high yields by reaction of aliphatic and aromatic carboxylic acids with one equivalent of diphenyl carbonate in the presence of catalytic amounts of tertiary amine bases, such as DBU, TBD and DMAP under neat conditions at elevated temperatures (>100°C).
Kreye, Oliver,Meier, Michael A. R.
p. 53155 - 53160
(2015/06/25)
Stereoselective nitration of olefins with tBuONO and TEMPO: Direct access to nitroolefins under metal-free conditions
Nitroolefins are essential elements for both synthetic chemistry and medicinal research. Despite significant improvements in nitration of olefin an efficient metal-free synthesis remains elusive so far. Herein, we disclose a new set of reagents to access nitroolefins in a single step under metal-free conditions. A wide range of olefins with diverse functionalities has been nitrated in synthetically useful yields. This transformation is operationally simple and exhibits excellent E-selectivity. Furthermore, site selective nitration in a complex setup makes this method advantageous.
Efficient and stereoselective nitration of mono- and disubstituted olefins with AgNO2 and TEMPO
Nitroolefin is a common and versatile reagent. Its synthesis from olefin is generally limited by the formation of mixture of cis and trans compounds. Here we report that silver nitrite (AgNO2) along with TEMPO can promote the regio- and stereoselective nitration of a broad range of olefins. This work discloses a new and efficient approach wherein starting from olefin, nitroalkane radical formation and subsequent transformations lead to the desired nitroolefin in a stereoselective manner.