Lithium Bis(1-methoxyvinyl)cuprate1,2

[56646-93-6]  · C6H10CuLiO2  · Lithium Bis(1-methoxyvinyl)cuprate  · (MW 184.65)

(vinylcuprate reagent and acyl anion equivalent which undergoes 1,4-addition reactions,3 substitution reactions,3 and reductive elimination reactions4)

Physical Data: yellow mixture, prepared in situ.

Solubility: sol THF.

Preparative Methods: by the slow addition of a -40 °C solution of 1-Methoxyvinyllithium5,6 to a solution of purified Copper(I) Iodide in a Dimethyl Sulfide-THF mixture (1:4 mole ratio of CuI:Me2S) at -40 °C; stirring for 30 min gives a yellow mixture.3

Handling, Storage, and Precautions: air- and moisture-sensitive reagent prepared in situ. Use in a fume hood.

Addition Reactions.

Lithium bis(1-methoxyvinyl)cuprate affords transfer of the 1-methoxyvinyl ligand, an acyl anion equivalent,7 via conjugate addition to a,b-alkenyl ketones (eq 1).3 This cuprate reaction is sensitive to the substitution patterns of the a,b-enone, especially at the C-3 and C-5 positions of cyclohexenone derivatives. The vinyl ether 1,4-adducts can be efficiently converted to either 1,4-diketones under dilute acidic conditions [0.025 N HCl/MeOH-H2O (4:1)] or 1,4-keto esters by ozonolysis in CH2Cl2-MeOH (9:1) at -60 °C.3

Substitution Reactions.

Lithium bis(1-methoxyvinyl)cuprate couples with Benzyl Bromide to afford a substitution product that, upon hydrolysis, yields 1-phenyl-2-propanone (eq 2). This reaction failed with 2-bromooctane.3

A lithium bis(1-methoxyvinyl)cyanocuprate reagent prepared from tetrakis(a-methoxyvinyl)tin reacts with Allyl Bromide to afford the coupling product in 60% yield.8

An allylic epoxide undergoes reaction with lithium bis(1-methoxyvinyl)cuprate to yield a substituted allylic alcohol (eq 3).9


g-Mesyl-a,b-enoates undergo reductive elimination with either lithium bis(1-methoxyvinyl)cuprate.BF3 or lithium bis(1-methoxyvinyl)cyanocuprate.BF3.2LiCl to afford b,g-enoates (eq 4) in excellent yield.4

Related Reagents.

1-Ethoxyvinyllithium; Lithium Bis(1-ethoxyvinyl)cuprate; Lithium (Z)-Bis(2-ethoxyvinyl)cuprate; Lithium Divinylcuprate.

1. Lipshutz, B. H.; Sengupta, S. OR 1992, 41, 135.
2. FF 1977, 6, 204.
3. Chavdarian, C. G.; Heathcock, C. H. JACS 1975, 97, 3822.
4. Fujii, N.; Habashita, H.; Shigemori, N.; Otaka, A.; Ibuka, T.; Tanaka, M.; Yamamoto, Y. TL 1991, 32, 4969.
5. Baldwin, J. E.; Höfle, G. A.; Lever, O. W., Jr. JACS 1974, 96, 7125.
6. Gschwend, H. W.; Rodriguez, H. R. OR 1979, 26, 1.
7. Lever, O. W., Jr. T 1976, 32, 1943.
8. Santiago, B.; Soderquist, J. A. JOC 1992, 57, 5844.
9. Bélanger, A.; Philibert, D.; Teutsch, G. Steroids 1981, 37, 361.

Christopher W. Alexander

Emory University, Atlanta, GA, USA

Robert K. Boeckman, Jr.

University of Rochester, NY, USA

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