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冯小明, Weiqing Yang, † Deju Shang, † Yanling Liu, † Ying Du, † and Xiaoming Feng*, †, ‡
J. Org. Chem., Vol. 70, No. 21, 2005,-0001,():
-1年11月30日
An efficient enantioselective approach to chiral dihydropyrones has been developed by the hetero-Diels-Alder (HDA) reactions of (E)-4-methoxy-2-trimethylsiloxy-penta-1,3-diene (diene 1) withaldehydes and pyruvates. It has been found that the readily accessible (R)-BINOL-Ti(OiPr)4(1.1:1) complex was a very effective catalyst for this reaction. Aromatic, heteroaromatic, conjugated,and aliphatic aldehydes afforded the corresponding products in moderate to high isolated yields(up to 99%) with excellent enantioselectivities (up to 99% ee). The first example of highlyenantioselective synthesis of 2,2,6-trisubstituted dihydropyrones by the catalytic reaction of diene1 with pyruvates was reported. The isolated intermediates indicated that this asymmetric HDAreaction proceeded in a Mukaiyama aldol pathway. On the basis of the absolute configurations ofthe products, a possible mechanism was proposed. Moreover, the catalytic system could be used tosynthesize a series of enantioenriched
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【期刊论文】Catalytic Asymmetric Cyanosilylation of Ketones by a Chiral Amino Acid Salt
冯小明, Xiaohua Liu, Bo Qin, Xin Zhou, Bin He, and Xiaoming Feng*
12224 9 J. AM. CHEM. SOC. 2005, 127, 12224-12225,-0001,():
-1年11月30日
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冯小明, Ke Cheng, Lili Lin, Shikui Chen and Xiaoming Feng*
Tetrahedron 61(2005)9594-9599,-0001,():
-1年11月30日
The aza-Diels–Alder reaction of trans-1-methoxy-2-methyl-3-trimethylsiloxybuta-1,3-diene with N-benzhydryl imines in the presence of Yb(OTf)3 in toluene at room temperature gave the corresponding 2,5-disubstituted 2,3-dihydro-4-pyridones in high yields. This reaction can also be carried out with diene, aldehydes, and amine in a three-component one-pot reaction manner in moderate to high yields under solvent-free conditions. The relationship between Lewis acids and activity, solvents and catalyst loading were studied. Some investigation towards the reaction mechanism was discussed.
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冯小明, Bo Gao, Zhengyan Fu, Zhipeng Yu, Lan Yu, Yaozong Huang and Xiaoming Feng*
Tetrahedron 61(2005)5822-5830,-0001,():
-1年11月30日
An efficient enantioselective approach to 2,5-disubstituted dihydropyrones was developed. Some easily accessible inexpensivediol ligand metal complexes were employed, and [(R)-BINOL]2–Ti(OiPr)4 complex was found to be the most effective catalyst (up to 99%yield and 99% ee in the presence of 5 mol% catalyst) for the hetero-Diels–Alder reaction between trans-1-methoxy-2-methyl-3-trimethylsiloxybuta-1,3-diene (1) and aldehydes. The potential and generality of this catalyst were evaluated by a variety of aldehydesincluding aromatic, heteroaromatic, a,b-unsaturated and aliphatic aldehydes. Based on the isolated intermediate from the reaction ofbenzaldehyde being confirmed by 1H, 13C NMR and HRMS data, the mechanism was proposed as a Mukaiyama aldol pathway.
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【期刊论文】Highly Enantioselective Cyanosilylation of Aldehydes Catalyzedby Novel
冯小明, Yan Li, † Bin He, † Bo Qin, † Xiaoming Feng, *, † and Guolin Zhang‡
J. Org. Chem. 2004, 69, 7910-7913,-0001,():
-1年11月30日
The
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