* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download 6. Low valent of Vanadium catalyst in organic synthesis
Fischer–Tropsch process wikipedia , lookup
Marcus theory wikipedia , lookup
Homoaromaticity wikipedia , lookup
Physical organic chemistry wikipedia , lookup
Elias James Corey wikipedia , lookup
Kinetic resolution wikipedia , lookup
Aromaticity wikipedia , lookup
Woodward–Hoffmann rules wikipedia , lookup
George S. Hammond wikipedia , lookup
Enantioselective synthesis wikipedia , lookup
1,3-Dipolar cycloaddition wikipedia , lookup
Organosulfur compounds wikipedia , lookup
Wolff rearrangement wikipedia , lookup
Aromatization wikipedia , lookup
Ene reaction wikipedia , lookup
Hofmann–Löffler reaction wikipedia , lookup
Vinylcyclopropane rearrangement wikipedia , lookup
Ring-closing metathesis wikipedia , lookup
Aldol reaction wikipedia , lookup
Tiffeneau–Demjanov rearrangement wikipedia , lookup
Discodermolide wikipedia , lookup
Asymmetric induction wikipedia , lookup
Strychnine total synthesis wikipedia , lookup
Petasis reaction wikipedia , lookup
Baylis–Hillman reaction wikipedia , lookup
Wolff–Kishner reduction wikipedia , lookup
Low valent of Vanadium catalyst in organic synthesis I. Oxidation of Alcohols *clean technological process and no halogenated solvents are involved Laxmidhar Rout, Adv. Synth. Catal. 2007, 349, 846 – 848 mechanism II.Pinacol Coupling Reaction 1. Secondary Aliphatic Aldehydes Toshikazu Hirao, J. Org. Chem. 1998, 63, 2812-281 mechanism Toshikazu Hirao, Top Curr Chem . 2007, 279: 53–75 2.intramolecular coupling reaction of 1,5diketone Toshikazu Hirao, J. Org. Chem. 1998, 63, 2812-2813 3.Aromatic aldehydes(solvent:water) No addition of a chlorosilane Xu, and Toshikazu Hirao J. Org. Chem., 2005, 70 (21), 8594-8596 4. aliphatic aldehydes with aromatic aldehyde(bearing a chiral auxiliary) • CAT:[V2Cl3(THF)6]2[Zn2Cl6] (V:II) • some aliphatic aldehydes + aromatic aldehyde(bearing a chiral auxiliary ) →1,2- diols • diastereoisomeric ratios up to 91:9 and enantiomeric excesses up to 84%. Tetrahedron:Asymmetry, 1990, 1(6), 355-358 III. Homocoupling 1. Coupling of Aldehydes The yield of 2a depended on the amount of chlorotrimethylsilane Toshikazu Hirao, J. Org. Chem. 1996, 61, 366-367 2.Coupling of Aldimines Bunpei Hatano, Akiya Ogawa, and Toshikazu Hirao* J. Org. Chem., 1998, 25, 9423. mechanism IV. Related Radical-Like Coupling Toshikazu Hirao, J. Org. Chem. 1998, 63, 2812-2813 [V2Cl3(THF)6]2,[Zn2Cl6],(V:II),freshly prepared from VCl3(THF)3 (V:III)by the reduction with Zn Tsutomu Inokuchi, J. Org. Chem., 1991, 16, 4983-4985 mechanism b:*Carried out in CH2Cl2-THF. Tsutomu Inokuchi, J. Org. Chem., 1991, 16, 4983-4985 Cyclization of Olefinic Iodoethers to Tetrahydrofurans Cp2TiCl2 was found to be superior to Cp2VCl2 as a catalyst under these reaction conditions Longhu Zhou, and Toshikazu Hirao J. Org. Chem., 2003, 68 (4), 1633-1635 V. stereoselective cyclodimerization Reaction conditions: benzylidene malononitrile (1 mmol), Cp2VCl2 (5 mol%), Zn (2 mmol), Me3SiCl (2 mmol), DMF (5 mL), Ar, rt, 3 h. Longhu Zhou and Toshikazu Hirao, Tetrahedron Letters, 2000, 41, 8517–8521 3a (24% yield with excellent diastereoselectivity (98:2) 2a (58% yield, 80:20) *3a was converted to 2a on treatment with silica gel overnight *18 h, only 2a was formed, VI. Dehalogenative Coupling *R2 is bigger. *the coordination of the phosphorus raises the reduction capability and selectivity. *the bulky reductant is liable to approach the bromide from the less hindered side Toshikazu Hirao,J. Org. Chem., 1993, 58 (23), 6529-6530 VII. A Novel C−C Single Bond Formation 1. V with Grinard reagent *cleavage of the C-O bond at the benzylic position was easy Yasutaka Kataoka,*J. Org. Chem. 1996, 61, 6094-6095 * clarify the effect of the added O2 As the amount of allyl bromide increased, the yield of the coupling product 1a decreased gradually while the amount of 3 increased. Mechanism: 1a, under high dilution conditions. Yasutaka Kataoka,*J. Org. Chem. 1997, 62, 8109-8113 The cleavage of the C-O bond at the allylic position also proceeded similarly. 2. V with ZnR2 the alkylation of carbonyl compounds the pinacolcoupling reaction the deoxygenative coupling reaction of carbonyl compounds Yasutaka Kataoka, J. Org. Chem. 1996, 61, 6094-6095 • a competitive reaction between an aldehyde and a ketone Yasutaka Kataoka, Isamu Makihira, Masaru Utsunomiya, J. Org. Chem., 1997, 62 (24), 8540-8543 3. V with Zn and allylic bromide *direct construction of asymmetric quaternary carbons Tetrahedron Letters, 1995, 36, 6495-6498 mechanism vanadium(II) species prepared in situ from VCl3(thf)3 and Zn VIII .cross-coupling reaction 1.Alkyl Halides with Aryl Griganard Reagents Br + ArMgBr Ar cat.VCl3 THF,25oC,1 h VCl3(0.05mmol) Br + PhMgBr (1.0mmol) THF,reflux,1 h Ph (50%) Mechanism: Br Ph Shigeo Yasuda,Hideki Yorimitsu* Bull.Chem.Soc. Jpn. 2008, 81, 287-290 Br VCl3(0.05mmol) PhMgBr(1.0mmol) THF,25oC,1 h,75% Ph 0.50mmol VCl3(0.05mmol) PhMgBr(1.0mmol) Br THF,25oC,1 h,45% 0.50mmol (16% recovery of the starting meterial) Prove the radical intermediate mechanism VCl3 4ArMgBr R-X ArMgBr - [Ar4VMgBr] [R-X] MgBr+ - [Ar4V] [Ar3V] X R R-Ar [RAr4V] IX. Potent Dinuclear Catalysts for Olefin Copolymerization