The reactiono fa lkynyl carboxylic acids, glyoxylic acid derivatives, and amines in the presence of ac opper catalyst afforded the corresponding propargyl amines in good yields. The alkynyl carboxylic acid of this coupling reaction shows similarr eactivity to that of at erminal alkyne, and the reactivityo ft he glyoxylic acid is almost identicalt ot hat of an aldehyde. When 2-aminopyridine was employed as the amine source, imidazopyridine derivatives weref ormedi n good yields.Scheme1.Different approaches to the synthesis of propargyl amines.[a] J.Supporting information and the ORCID identification number(s) for the author(s) of this article can be found under http://dx.
Arylsulfonyl hydrazides were employed as coupling partners for the decarboxylative coupling reaction of propiolic acid derivatives. When the reaction was conducted using Pd(TFA)2 (1.0 mol%), dppp (1.0 mol%), and Cu(OAc)2 (2.4 equiv) in DMF at 100 °C for 0.5 hour, the desired coupled products were formed in moderate to good yields. The reaction showed good tolerance toward functional groups such as ester, ketone, cyano, nitro, chloro, and bromo groups.
A double decarboxylative coupling reaction was developed. Alkynyl carboxylic acids, glyoxylic acid, and amines were reacted in the presence of a copper catalyst to afford the corresponding propargyl amines in good yields. It was found that the alkynyl carboxylic acid showed similar reactivity to a terminal alkyne, and the reactivity of glyoxylic acid was almost identical to that of an aldehyde in this coupling reaction. More information can be found in the full paper by S. Lee and co‐workers on page 770 in Issue 6, 2016 (DOI: 10.1002/ajoc.201600109).
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