Direct Amidation of Carboxylic Acids through an Active α-Acyl Enol Ester Intermediate
作者:Xianjun Xu、Huangdi Feng、Liliang Huang、Xiaohui Liu
DOI:10.1021/acs.joc.8b00819
日期:2018.8.3
The development of a highly efficient and simple protocol for the direct amidation of carboxylic acids is described employing ynoates as novel coupling reagents. The transformation proceeds in good to excellent yields via in situ α-acyl enol ester intermediatesformation under mild reaction conditions. This useful method has been demonstrated for a range of substrates to provide a succinct access to
induced by ultraviolet (UV) light. Forty-six examples with various functional groups are explored at room temperature with irradiation by three 26 W UV lamps (350–380 nm). The yield reaches 97%. The gram scale experiment product yield is 76%. Moreover, this system can be applied to the synthesis of several amino acid derivatives. Mechanistic studies show that benzoin is generated in situ from benzil under
A new strategy to construct allylamines through reductive alkenylation of secondary amides with enamines is reported. The method features the use of trifluoromethanesulfonic anhydride as an activation reagent of amides, and enamines as unconventional alkenylation reagents. In this manner, enamines serve as surrogates of alkene carbanions instead of the classical enolates equivalents. A possible mechanism
An Efficient Catalytic Amidation of Esters Promoted by N-Heterocyclic Carbenes
作者:Ling-Yan Chen、Mei-Fang Wu
DOI:10.1055/s-0037-1610355
日期:2019.4
amidation between esters and amines or hydrazines is described. This strategy was tolerant for a wide scope of substrates, affording a series of amides (or hydrazides) in good to excellent yields (60–96%) under simple conditions. The approach was also used to synthesize the pharmaceutically relevant antidepressant moclobemide in 85% yield. An efficient NHC-catalyzed amidation between esters and amines or
Under photocatalytic reductive conditions, trifluoromethylradical addition onto an ynamide followed by cyclization on a benzoyl moiety produces diverse isoindolinone platforms with good yields. The selectivity of the radical cyclization, N-benzoyl vs. N-benzyl as radical acceptor and the E/Z ratio of isomers have been rationalized by modeling.