Gold-catalyzed intramolecular hydroamination of α-amino allenamides as a route to enantiopure 2-vinylimidazolidinones

Allenamides: A Powerful and Versatile Building Block in Organic Synthesis

“…Broggini 62 reported an Au(III)-catalyzed intramolecular hydroamination of allenamides 174 , which afforded a mixture of cis - and trans 2-vinylimidazolidines 177 through the 5- exo -trig transition states 175 and 176 , respectively. Intriguingly, when R = Bn, only cis - 177 was isolated in good yield (Scheme 52).…”

Transition‐Metal‐Catalyzed Hydroamination Reactions

“…This reaction has been investigated by various research groups, and pioneering work in allene hydroamination focused on the use of early transition metal and rare earth elements [12,219]. In the past 10 years, late transition metals have shown particularly interesting applications in the intramolecular version of this reaction [220][221][222][223]. Owing to the commonly cited enhanced functional group tolerance of late transition metals, many groups have pursued their application in the selective synthesis of functionalized heterocycles.…”

“…In intramolecular reactions, modest yields can be obtained using these highly functionalized cyclohydroamination substrates, and notably, most examples make use of protected nitrogen. However, one example of a dialkylamine functionality could be used for ring closure (Scheme 15.48) [223]. Yamamoto and coworkers probed the mechanism of the previously reported intermolecular hydroamination of allenes with aryl-and alkylamines using Au(III) and Au(I) salts.…”

“…In late transition metals, where many reactions have been shown to proceed via outer-sphere amine addition to coordinated alkene, it is challenging to control such additions distal to the metal. Furthermore, more recent results [218,223,261,267,272], which show the propensity for late transition metals with no auxiliary ligands to mediate alkene hydroamination, point toward the importance of metal complex design in ensuring that chiral auxiliary ligands are not displaced under catalytic conditions.…”

A simple one-pot preparation of N-allenyl amides, ureas, carbamates and sulfonamides using a DMSO/tBuOK protocol

“…In continuation of our interest in allenamides 6 in Au-catalysed transformations, [7][8][9][10][11][12] we present a technically simple, yet robust 'one-pot' approach to synthesising these valuable building blocks using an adapted protocol of Heaney and Ley. 13 We reported in 2010 6c that treatment of 2-oxazolidinone (9) and excess propargyl bromide (2) with a mixture of DMSO/ t BuOK was sufficient for full conversion into the N-allenyl carbamate 10 in an isolated yield of 68% (Scheme 2).…”