Organozinc Reagents

© Hans J. Reich 2004

Reformatsky Reaction

The Reformatsky reaction involves the reduction of an α-carbonyl compound (usually an ester) with zinc to form a zinc enolate, which condenses with an adehyde or ketone. Classically the reaction was performed under Barbier conditions (ketone, halide and zinc mixed), but separate preparation of the reagent has some significant advantages.

The X-ray structure of a Reformatsky reagent has been reported (Dekker, J. Chem. Commun. 1983, 553). Both carbon and oxygen are bonded to zinc.

  

Ketone zinc enolates seem to be O-zincated (Hansen, M. M.; Bartlett, P. A.; Heathcock, C. H. Organometallics., 1987, 6, 2069)

The Reformatsky Reaction,
  Rathke, M. W. Org. React. 1975, 22, 423.
  Shriner, R. L. Org. React. 1942, 1, 1.
Recent Advances in the Reformatsky Reactions,
  Furstner, A. Synthesis 1989, 571

  
  
  
  
  
  
  
  

Simmons-Smith Reaction

The Simmons-Smith reaction involves the cyclopropanation of alkenes by a halomethylzinc reagent (usually ICH2ZnI, but also ICH2ZnCH2I) prepared by reaction of methylene iodide with Zn or ZnEt2. The reaction occurs with all reasonably electron rich alkenes (there is a small preference for electron rich alkenes), but works especially well for allylic alcohols and ethers, where chelation of Zn to the oxygen apparently plays an important role in both increasing the rate and controlling the stereochemistry.

  

Simmons Smith Reaction:
Cyclopropanes from Unsaturated Compounds, Methylene Iodide, and Zinc-Copper Couple
  Simmons, H. E.; Cairns, T. L.; Vladuchick, S. A. Org. React. 1973, 20, 1
The Asymmetric Cyclopropanation of Acyclic Allylic Alcohols: Efficient Stereocontrol with Iodomethylzinc Reagents,
  Charette, A.B.; Marcoux, J.-F. Synlett 1995, 1197-207.
Bis(iodozincio)methane - Preparation, Structure, and Reaction.
  Matsubara, S.; Oshima, K.; Utimoto, K. J. Organomet. Chem. 2001, 617-8, 39-46.

  

Carbometalation with Zinc Reagents

In the example below, neither the lithium nor the magnesium reagent does an intramolecular addition to the alkene, but the zinc reagent adds smoothly

  

Even well-stabilized zinc reagents will add intramolecularly to olefins. Lorthiois, Marek, Normant J. Org. Chem. 1998, 63, 2442; Karoyan, Quancard, Vaissermann, Chassaing J. Org. Chem. 2003, 68, 2256

  

An astonishing reaction is the addition of zinc reagents to vinyllithium and Grignard reagents, to form a 1,1-bisorganometallic: Normant J. Org. Chem. 1995, 60, 2488; Knochel, P.; Normant, J. F. Tetrahedron Lett. 1986, 27, 1039, 1043.

  

Organozinc Chemistry:

Enantioselective Addition of Organometallic Reagents to Carbonyl Compounds; Chirality Transfer, Multiplication and Amplification,
  Noyori, R.; Kitamura, M. Ang. Chem. Int. Ed. 1991, 30, 49.
Enantioselective Addition of Organozinc Reagents to Aldehydes,
  Soai, K.; Niwa, S. Chem. Rev. 1992, 92, 833.
Transition Metal Catalyzed Reactions of Organozinc Reagents,
  Erdik, E. Tetrahedron 1992, 48, 9577.
Preparation and Reactions of Polyfunctional Organozinc Reagents in Organic Synthesis,
  Knochel, P.; Singer, R. D. Chem. Rev. 1993, 93, 2117.
The Role of Zinc Carbenoids in Organic Synthesis,
  Motherwell, W.B.; Nutley, C. J. Contemporary Organic Synthesis 1994, 1, 219.
Preparation of Carbocyclic and Heterocyclic Compounds by the use of Allylzinc and Heterocyclic Compounds by the use of Allylzinc and an Allylpalladium in Tandem,
  van der Baan, J.L.; van der Heide, T.A.J.; van der Louw, J.; Klumpp, G.W. Synlett, 1995, 1.
Organozinc Reagents in Organic Synthesis,
  Erdik, E. CRC Press: Boca Raton, FL, 1996.
Organozinc Mediated Reactions,
  Knochel, P.; Perea, J. J. A.; Jones, P. Tetrahedron 1998, 54, 8275-319.
Organozinc Reagents: A Practical Approach,
  Knochel, P.; Joned, P., Eds. Oxford University Press: Oxford, U.K., 1999.
Rational Design of Chiral Catalysis for the Enantioselective Addition Reaction of Dialkylzincs,
  Soai, K. Enantiomer 1999, 4, 591-8.
The Discovery of Novel Reactivity in the Development of C-C Bond-Forming Reactions: In Situ Generation of Zinc Acetylides with ZnII/R3N,
  Frantz, D. E.; Faessler, R.; Tomooka, C. S.; Carreira, E. M. Acc. Chem. Res. 2000, 33, 373-81.
New Applications of Polyfunctional Organometallic Compounds in Organic Synthesis.
  Boudier, A.; Bromm, L. O.; Lotz, M.; Knochel, P. Angew. Chem. Int. Ed. Engl. 2000, 39, 4415-35.
Catalytic Asymmetric Organozinc Additions to Carbonyl Compounds.
  Pu, L.; Yu, H.-B. Chem. Rev. 2001, 101, 757-824

Bimetallic Zinc Reagents:
Synthesis and Reactivity of sp3-Geminated Organodimetallics,
  Marek, I.; Normant, J.-F. Chem. Rev. 1996, 96, 3241-68.
Stereoselective Reactions Mediated by Functionalized Diorganozincs,
  Knochel, P. Synlett 1995, 393-403.


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