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1、 Key Laboratory of Green Chemistry Pavel Kocovsk , Eur. J. Org. Chem. 2007, 29. 4.G. Chelucci, G. Marineddu, G. A. Pinna, Tetrahedron: Asymmetry 2004, 15, 1373. biquinoline biquinoline N N- -oxideoxide pyridine or quinolinepyridine or quinoline- -type Ntype N- -oxides oxides The oxygen 2p electrons
2、are conjugated with the N-heteroaromatic ring. The nitrogen of the N-oxide moiety is achiral. Chiral Biquinoline N,N-Dioxide a.Bo Liu, Xiaoming Feng*, et al, Synlett 2001, 1501. b.Zhigang Jiao, Xiaoming Feng*, Eur J. Org. Chem. 2003, 3818. Bifunctional Catalyst System Y.-C. Shen, X.-M. Feng, G.-L. Z
3、hang, Y.-Z. Jiang, Synlett. 2002, 1353. Y.-C. Shen, X.-M. Feng, Y. Li, G.-L. Zhang, Y.-Z. Jiang, Eur. J. Org. Chem. 2004, 129. titanium complex of mono N-oxide Diarylprolinol-based structure hyper silicon intermediate N-oxide is approximately tetrahedral with chirality. Design of Bifunctional C2- Sy
4、mmetric N,N-Dioxide Compounds combining the key characteristics of the catalysts for multidentate bifunctional catalysis Synthesis of Chiral N,N-Dioxide Amides Inexpensive Convenitent to manipulate Amenable to Structural modification Stable Representative Structures of Chiral N,N-Dioxides The stereo
5、selective oxidation and formation of six-membered hydrogen-bonded rings were confirmed by NMR and X-ray analysis of N,N-dioxides. alkyl chain alkyl chain Diamine-linker Aryl-linker BINOL-linker Naming of the ligands Representative Structures of Chiral N,N-Dioxides X-ray structure of L-PiPr X-ray str
6、ucture of L-RiPr Varied stereo-arrangement of N,N-dioxides bearing different amino acid backbone shows the conformational flexibility of the compounds. H-bonding H-bonding opposite site of the linker same site of the linker Asymmetric Cyanosilylation of Aldehydes, Ketones and Imines Further Applicat
7、ions? -Chiral Ligands Sc Mg Fe Co Ni Cu Zn In Ag Y La Nd Sm Gd Yb A wild variety of metal cations can associate with chiral N,N-dioxides to form efficient catalysts, including rare-earth metals, the transition metals, and main group metals. Further Applications? -Chiral Ligands Acc. Chem. Res. 2011,
8、 574; Chem. Rev. 2011, 6947; Org. Chem. Front. 2014, 1, 298. Chemoselectivity - Intrinsic problem of the classic Roskamp reaction Stereoselective strategy: Asymmetric Roskamp Reaction The reaction process might undergo three rearrangement pathways once the diazonium intermediate generated. That is t
9、he shift competition of hydrogen, oxygen or alkyl group. Roskamp reaction using -alkyl-diazoesters could provide chiral -alkyl-keto esters. Racemization of the product is a big problem. Two stereoselective examples reported by Prof. Maruoka entry ligand metal time (h) yield (%) ee (%) 1 L-PiPr2 Zn(O
10、Tf)2 29 8 55 2 L-PiPr2 Sm(OTf)3/Y(OTf)3 / La(OTf)3/Yb(OTf)3 29 N.R. - 3 L-PiPr2 Sc(OTf)3 7 95 78 4 L-PrPr2 Sc(OTf)3 7 90 75 1,2-H shift Sc 1H NMR after chromotography separation 1H NMR after flash filtration Flash filtration is enough for purify of the product. No enol ester existed in aprotic solve
11、nt. entry ligand additive L:ScIII x (mol%) time (h) ee (%) yield (%) 1 L-RiPr2 - 1:1 5 7 94 97 2 L-RiPh - 1:1 5 29 40 10 3b L-RiPr2 3 MS 1:1 5 2 94 97 4b,c,d L-RiPr2 3 MS 1:1.2 0.05 2 95 97 5b,c,e L-RiPr2 3 MS 1:1.2 0.01 56 95 80 a L/Sc(OTf)3 (1/1), 0.1 mmol 1a and 0.1 mmol 2a in 0.5 mL CH2Cl2 at -2
12、0 oC. b 3 MS (10.0 mg) was added. c L-RiPr2/Sc(OTf)3 (1/1.2), 1.0 mmol 1a and 1.0 mmol 2a. d 0.2 mL CH2Cl2 was used. e 0.1 mL CH2Cl2 was used. Li, W.; Wang, J.; Wang, W. T.; Lin, L. L.; Liu, X. H.; Feng, X. M. J. Am. Chem. Soc. 2010, 132, 8532. Aliphatic aldehydes failed. Enantioselective Roskamp re
13、action catalyzed by oxazaborolidinium ion Prof. D. H. Ryu*, Angew. Chem. Int. Ed. 2012, 51, 8322. Roskamp-Feng反应 (Synfacts 2012, 8, 63) 首例重氮酯的不对称亲电加成反应 被Synfacts评价“照亮了重氮化学 的多样性” “The reaction shed light on the diversity of diazo chemistry”. Elsevier公司出版社公司出版社 （2011年年12月出版）月出版） 手性氮氧酰胺Sc(III)配合物催化不对 称
14、Roskamp反应被编入专著Organic Synthesis Based on Name Reactions(第三版, 2011, Elsevier出 版 社 , 408 页 ) ， 并 被 冠 名 为 “RoskampFeng反应”。 Roskamp-Feng Reaction was named in Organic Synthesis Based on Name Reaction “Any stereogenic centre next to a carbonyl group is precarious because enolization will destroy it. It w
15、ould be foolish to try and make optically active -keto esters whose only stereogenic centre was between the two carbonyl groups. Although the keto-ester is chiral, the enol is flat and cannot be chiral. The two forms are in rapid equilibrium so all optical activity would quickly be lost.” 摘自：Clayden
16、, J.; Greeves, N.; Warren, S; Oxford University Press: Organic Chemistry, New York, 2012; pp 459-460. 尝试制备手性中心位于两个羰基之间的光学活性-酮酯可能是愚蠢的。 F. Dean. Toste, J. Am. Chem. Soc. 2004, 126, 15978; J. Am. Chem. Soc. 2006, 128, 8132. The Stereoselective Propargyl Rearrangements: Marisa C. Kozlowski Angew. Chem. Int. Ed. 2012, 51, 2448. propargyl rearrangements using optically acti
