Synthetic reactions driven by electron-donor–acceptor (EDA) complexes

• Zhonglie Yang,
• Yutong Liu,
• Kun Cao,
• Xiaobin Zhang,
• Hezhong Jiang and
• Jiahong Li

Beilstein J. Org. Chem. 2021, 17, 771–799, doi:10.3762/bjoc.17.67

• perfluoroalkylation of unactivated olefins can be realized with phosphine catalyst and perfluorobutyl iodide (28) under visible-light irradiation. The EDA complex formed by perfluorobutyl iodide (28) and phosphine catalyst induced SET, affording a perfluoroalkyl radical, and then perfluoroalkylation product 97 was

All-carbon [3 + 2] cycloaddition in natural product synthesis

• Zhuo Wang and
• Junyang Liu

Beilstein J. Org. Chem. 2020, 16, 3015–3031, doi:10.3762/bjoc.16.251

• -workers proposed that the catalytic mechanism involves a reaction between phosphine catalyst A and allene 82 to give B and/or C (Scheme 5B). Catalytic [3 + 2] cycloaddition of B and/or C and alkene D gives the cyclic intermediates E and F in an equilibrium state through a 1,2-proton transfer. The loss of

• phosphine catalyst from E or F affords the cycloaddition product G and the catalyst is regenerated. It is noteworthy that ethyl 2-butynoate (85) can be used as substrate in place of ethyl 2,3-butadienoate (82) in the phosphine-catalyzed [3 + 2] cycloaddition. Ethyl 2-butynoate (85) enters the catalytic

• cycle by reacting with phosphine catalyst A to give H and C. Some total syntheses of hexacyclic Daphniphyllum alkaloids were reported by Li’s group (longeracinphyllin A (10) [41] and daphenylline (11) [42]) and Zhai’s group (daphenylline (11) [43]), applying Lu’s [3 + 2] cycloaddition (Scheme 6). The

Enantioconvergent catalysis

• Justin T. Mohr,
• Jared T. Moore and
• Brian M. Stoltz

Beilstein J. Org. Chem. 2016, 12, 2038–2045, doi:10.3762/bjoc.12.192

• enantiopure phosphine catalyst 27 in order to generate the coupled product 30 with both high ee and dr (Scheme 6) [31]. Presumably, the allenyl stereochemistry is destroyed upon 1,4-addition of the phosphine catalyst, resulting in chiral phosphonium adduct 29 that further reacts with deprotonated oxazole 28

1H-Imidazol-4(5H)-ones and thiazol-4(5H)-ones as emerging pronucleophiles in asymmetric catalysis

• Antonia Mielgo and
• Claudio Palomo

Beilstein J. Org. Chem. 2016, 12, 918–936, doi:10.3762/bjoc.12.90

• ] pronucleophiles to γ-substituted allenoates and/or alkynoates in the presence of a C2-symmetric chiral phosphine catalyst. Although γ-substituted allenes have been employed in many phosphine-mediated γ-additions, to date there was virtually no progress on the use of prochiral pronucleophiles in phosphine-mediated

• . Then this basic intermediate is proposed to deprotonate the starting thiazolone thus providing enolate V, which subsequently adds to the γ-carbon of IV to afford intermediate VI. After proton shift, intermediate VI becomes intermediate VII and this eliminates the phosphine catalyst, which enters a new

Asymmetric α-amination of 3-substituted oxindoles using chiral bifunctional phosphine catalysts

• Qiao-Wen Jin,
• Zhuo Chai,
• You-Ming Huang,
• Gang Zou and
• Gang Zhao

Beilstein J. Org. Chem. 2016, 12, 725–731, doi:10.3762/bjoc.12.72

• catalysts is reported. The corresponding products containing a tetrasubstituted carbon center attached to a nitrogen atom at the C-3 position of the oxindole were obtained in high yields and with up to 98% ee. Keywords: 3-aminooxindoles; asymmetric catalysis; phosphine catalyst; tetrasubstituted

Enantioselective [3 + 2] annulation of α-substituted allenoates with β,γ-unsaturated N-sulfonylimines catalyzed by a bifunctional dipeptide phosphine

• Huanzhen Ni,
• Weijun Yao and
• Yixin Lu

Beilstein J. Org. Chem. 2016, 12, 343–348, doi:10.3762/bjoc.12.37

• of a dipeptide phosphine catalyst, a wide range of highly functionalized cyclopentenes bearing an all-carbon quaternary center were obtained in moderate to good yields and with good to excellent enantioselectivities. Keywords: [3 + 2] annulation; α-substituted allenoate; dipeptide phosphine

• phosphine catalyst furnishes the final [3 + 2] annulation product 5. Conclusion In conclusion, we have described the first enantioselective [3 + 2] cycloaddition of α-substituted allenoates with β,γ-unsaturated N-sulfonylimines, catalyzed by amino acid-derived bifunctional phosphines. The [3 + 2] annulation

Chiral phosphines in nucleophilic organocatalysis

• Yumei Xiao,
• Zhanhu Sun,
• Hongchao Guo and
• Ohyun Kwon

Beilstein J. Org. Chem. 2014, 10, 2089–2121, doi:10.3762/bjoc.10.218

• yields and ee’s. In 2007, based on their peptide catalyst studies, the Miller group developed the first α-amino acid-based phosphine catalyst H1 for enantioselective [3 + 2] annulations of allenoates with enones (Scheme 21) [52]. This catalyst performed multiple roles during the catalytic process, with

• alkenes and MBH adducts, albeit in slightly diminished yields. Shi and co-workers also studied this reaction, but using the chiral bifunctional thiourea-phosphine catalyst G7. The [3 + 2] annulation of MBH carbonate with an activated isatin-based alkene in toluene at room temperature gave the

• corresponding γ-cycloadduct as the major product in 92% yield, with 9:1 dr and 74% ee [77]. Using the amino acid-derived chiral phosphine catalyst H11, Lu and co-workers performed asymmetric [3 + 2] annulations between MBH carbonates and maleimides, obtaining access to a wide range of bicyclic imides in

The catalytic performance of Ru–NHC alkylidene complexes: PCy₃ versus pyridine as the dissociating ligand

• Stefan Krehl,
• Diana Geißler,
• Sylvia Hauke,
• Oliver Kunz,
• Lucia Staude and
• Bernd Schmidt

Beilstein J. Org. Chem. 2010, 6, 1188–1198, doi:10.3762/bjoc.6.136

• deactivation side for phosphine catalyst E, and to the enhanced initiation side for pyridine catalyst H. The most remarkable result from this set of experiments, however, is a collapse of conversion if benzylidene catalyst D is used in acetic acid. With D, a reproducible conversion of only 9% to the

Suzuki–Miyaura cross-coupling reaction of 1-aryltriazenes with arylboronic acids catalyzed by a recyclable polymer-supported N-heterocyclic carbene–palladium complex catalyst

• Guangming Nan,
• Fang Ren and
• Meiming Luo

Beilstein J. Org. Chem. 2010, 6, No. 70, doi:10.3762/bjoc.6.70

• , while the homogeneous Pd-phosphine catalyst system gave very low product yields with these substrates [29]. The good reactivity and chemoselectivity may allow haloaryltriazenes to be used as substrates for differential cross-coupling reactions in the same way as haloarenediazonium salts [33]. Conclusion