Gold-catalyzed ethylene cyclopropanation

• Silvia G. Rull,
• Andrea Olmos and
• Pedro J. Pérez

Beilstein J. Org. Chem. 2019, 15, 67–71, doi:10.3762/bjoc.15.7

• transfer; cyclopropane; cyclopropylcarboxylate; ethylene cyclopropanation; ethyl diazoacetate; gold catalysis; Introduction Nowadays the olefin cyclopropanation through metal-catalyzed carbene transfer starting from diazo compounds to give olefins constitutes a well-developed tool (Scheme 1a), with an

• compounds bearing a carboxylate substituent are the most commonly employed carbene precursors toward olefin cyclopropanation, their use with ethylene leads to cyclopropane (Scheme 1b). De Bruin and co-workers have described [4] such product in a minor, secondary reaction (yields <12%) while studying the

• . The complex TpMsCu(thf), previously described as an excellent catalyst for olefin cyclopropanation [18], led to negative results, since only the olefins 2 (mixtures of diethyl fumarate and maleate) were detected at the end of the reaction. The second copper-based catalyst tested Tp(CF3)2,BrCu(thf) [19

Evidencing an inner-sphere mechanism for NHC-Au(I)-catalyzed carbene-transfer reactions from ethyl diazoacetate

• Manuel R. Fructos,
• Juan Urbano,
• M. Mar Díaz-Requejo and
• Pedro J. Pérez

Beilstein J. Org. Chem. 2015, 11, 2254–2260, doi:10.3762/bjoc.11.245

• functionalization; olefin cyclopropanation; Introduction The discovery of the catalytic capabilities of soluble gold(I) species toward the hydration of alkynes by Teles and co-workers [1] is considered as the rising of the golden era for the use of this metal in homogeneous catalysis [2][3]. A number of

• reaction (olefin cyclopropanation). (b) Side-reactions of carbene or diazo coupling commonly observed. The outer- and inner-sphere routes for this transformation. Acknowledgements Support for this work was provided by the MINECO (CTQ2014-52769-C3-1-R), and the Junta de Andalucía (P10-FQM-06292).

Synthesis of chiral N-phosphoryl aziridines through enantioselective aziridination of alkenes with phosphoryl azide via Co(II)-based metalloradical catalysis

• Jingran Tao,
• Li-Mei Jin and
• X. Peter Zhang

Beilstein J. Org. Chem. 2014, 10, 1282–1289, doi:10.3762/bjoc.10.129

• poor yield (Table 1, entry 8). To our delight, the use of catalyst [Co(P5)] (P5 = 3,5-DitBu-QingPhyrin), which was shown to be effective in asymmetric intramolecular olefin cyclopropanation [37], led to significant further improvement in enantioselectivity to 81% ee although the yield for the

Recent developments in gold-catalyzed cycloaddition reactions

• Fernando López and
• José L. Mascareñas

Beilstein J. Org. Chem. 2011, 7, 1075–1094, doi:10.3762/bjoc.7.124

• with alkenes [70]. Gold-catalyzed intermolecular hetero-dehydro Diels–Alder cycloaddition [72]. Gold(I)-catalyzed stereoselective olefin cyclopropanation [74]. Reaction of propargylic benzoates with α,β-unsaturated imines to give azepine cycloadducts [77]. Gold-catalyzed (3 + 3) annulation of

When cyclopropenes meet gold catalysts

• Frédéric Miege,
• Christophe Meyer and
• Janine Cossy

Beilstein J. Org. Chem. 2011, 7, 717–734, doi:10.3762/bjoc.7.82

• in this review, these structural effects were found to have important consequences in terms of reactivity in the case of intermolecular olefin cyclopropanation promoted by gold carbenes generated from cyclopropenes. In fact, the first reports on gold-catalyzed reactions involving cyclopropenes

• impact of cationic versus carbene-like species on the reactivity in olefin cyclopropanation [17]. In the presence of an olefin and a cationic gold(I) catalyst, cyclopropenone acetal 3 did not provide any cyclopropanation product, which is in agreement with the fact that the organogold species generated

• moderate results, whereas the highest yield and diastereoselectivity was obtained when the strong σ donor and weak π acceptor N-heterocyclic carbene IPr was the ligand. The latter was indeed anticipated to give an organogold with a higher carbene-like reactivity which favors olefin cyclopropanation. AuCl