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Low valent of Vanadium catalyst in organic synthesis

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.

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Low valent of Vanadium catalyst in organic synthesis

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  1. Low valent of Vanadium catalystin organic synthesis

  2. I. Oxidation of Alcohols *clean technological process and no halogenated solvents are involved Laxmidhar Rout, Adv. Synth. Catal. 2007, 349, 846 – 848

  3. mechanism

  4. II.Pinacol Coupling Reaction 1. Secondary Aliphatic Aldehydes Toshikazu Hirao,J. Org. Chem. 1998, 63, 2812-2813

  5. mechanism Toshikazu Hirao, Top Curr Chem . 2007, 279: 53–75

  6. 2.intramolecular coupling reaction of 1,5-diketone Toshikazu Hirao,J. Org. Chem. 1998, 63, 2812-2813

  7. 3.Aromatic aldehydes（solvent：water） No addition of a chlorosilane Xu, and Toshikazu Hirao J. Org. Chem., 2005, 70 (21), 8594-8596

  8. 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

  9. 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

  10. 2.Coupling of Aldimines Bunpei Hatano, Akiya Ogawa, and Toshikazu Hirao* J. Org. Chem., 1998, 25, 9423.

  11. mechanism

  12. IV. Related Radical-Like Coupling Toshikazu Hirao,J. Org. Chem. 1998, 63, 2812-2813

  13. [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

  14. mechanism

  15. b:*Carried out in CH2Cl2-THF.

  16. Tsutomu Inokuchi, J. Org. Chem., 1991, 16, 4983-4985

  17. 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

  18. 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

  19. 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,

  20. 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

  21. 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

  22. * 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.

  23. Mechanism: 1a, under high dilution conditions. Yasutaka Kataoka,*J. Org. Chem. 1997, 62, 8109-8113

  24. The cleavage of the C-O bond at the allylic position also proceeded similarly.

  25. 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

  26. a competitive reaction between an aldehyde and a ketone Yasutaka Kataoka, Isamu Makihira, Masaru Utsunomiya, J. Org. Chem., 1997, 62 (24), 8540-8543

  27. *direct construction of asymmetric quaternary carbons 3. V with Zn and allylic bromide Tetrahedron Letters, 1995, 36, 6495-6498

  28. mechanism vanadium(II) species prepared in situ from VCl3(thf)3 and Zn

  29. VIII .cross-coupling reaction 1.Alkyl Halides with Aryl Griganard Reagents Mechanism： Shigeo Yasuda,Hideki Yorimitsu* Bull.Chem.Soc. Jpn. 2008, 81, 287-290

  30. Prove the radical intermediate

  31. mechanism

  32. IX. Potent Dinuclear Catalysts for Olefin Copolymerization

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