434283-63-3Relevant academic research and scientific papers
Asymmetric Synthesis of α-Alkylidene-β-Lactams through Copper Catalysis with a Prolinol-Phosphine Chiral Ligand
Imai, Koji,Takayama, Yurie,Murayama, Hiroaki,Ohmiya, Hirohisa,Shimizu, Yohei,Sawamura, Masaya
supporting information, p. 1717 - 1721 (2019/03/12)
A copper/prolinol-phosphine chiral catalyst enabled the one-step synthesis of chiral α-alkylidene-β-lactams. Optimization of the chiral ligand for steric and electronic properties realized the highly enantioselective coupling of nitrones and propargyl alcohol derived alkynes. The resulting chiral α-alkylidene-β-lactams served as a platform for various β-lactams via well-established transformations of α,β-unsaturated carbonyl compounds.
Asymmetric Synthesis of β-Lactams through Copper-Catalyzed Alkyne–Nitrone Coupling with a Prolinol–Phosphine Chiral Ligand
Takayama, Yurie,Ishii, Takaoki,Ohmiya, Hirohisa,Iwai, Tomohiro,Schwarzer, Martin C.,Mori, Seiji,Taniguchi, Tohru,Monde, Kenji,Sawamura, Masaya
supporting information, p. 8400 - 8404 (2017/06/28)
Prolinol–phosphine chiral ligands enabled highly enantioselective copper-catalyzed intermolecular alkyne–nitrone coupling (Kinugasa reaction) to produce 1,3,4-trisubstituted chiral β-lactams. A high level of enantiocontrol was achieved not only with aryl- or alkenylacetylenes but also with alkylacetylenes, which were important but unfavorable substrates in the previously reported protocols. Two-point hydrogen bonding between the chiral ligand and the nitrone oxyanion consisting of O?H???O and C(sp3)?H???O hydrogen bonds is proposed.
A highly stereoselective synthesis of chiral α-amino-β-lactams via the Kinugasa reaction employing ynamides
Zhang, Xuejun,Hsung, Richard P.,Li, Hongyan,Zhang, Yu,Johnson, Whitney L.,Figueroa, Ruth
supporting information; experimental part, p. 3477 - 3479 (2009/05/27)
(Chemical Equation Presented) A highly stereoselective synthesis of chiral α-amino-β-lactam through an ynamide-Kinugasa reaction is described. In addition, a mechanistic model is illustrated here to rationalize the observed diastereoselectivity, which depends on both the initial [3 + 2] cycloaddition step and the subsequent protonation for which both are highly selective.
Cu(I)/Bis(azaferrocene)-catalyzed enantioselective synthesis of β-lactams via couplings of alkynes with nitrones
Lo, Michael M.-C.,Fu, Gregory C.
, p. 4572 - 4573 (2007/10/03)
As a consequence of the wide-ranging significance of β-lactams (e.g., use as drugs and as chiral building blocks), a great deal of effort has been dedicated to the development of methods for their stereoselective synthesis. Although considerable progress has been achieved, nearly all of the approaches that have been described are based on the use of chiral precursors; direct catalytic enantioselective routes to β-lactams are rare as well as limited in scope. In this communication, we establish that, using a new C2-symmetric planar-chiral bis(azaferrocene) ligand, we can generate β-lactams with very good enantiomeric excess and cis diastereoselection via catalytic enantioselective Kinugasa reactions (couplings of alkynes with nitrones). Appealing attributes of this process include the ready availability of the starting materials, the functional-group tolerance of the reaction, and the convergency of the approach. Copyright
