[4843-71-4]  · C4H5Li  · 1,3-Butadienyl-1-lithium  · (MW 60.02) (E)


(reagent for single-step introduction of the 1,3-butadienyl group)

Solubility: sol THF and ether.

Preparative Method: (E)-1,3-butadienyl-1-lithium was generated from (E)-butadienyltributylstannane and BuLi in hexane at -78 °C for 15 min.1 Concentration of the reagent solution can be determined by titration.2

Handling, Storage, and Precautions: the reagent is moisture- and air-sensitive. All solvents must be dried before use.

1,3-Butadienyl-1-lithium Reagents.

A common approach for the preparation of the 1,3-butadienyl-1-lithium reagents is transmetalation of butadienyltrialkylstannanes with Methyllithium3 or n-Butyllithium.1,3-7 Rapid transmetalation proceeds with complete retention of diene configuration (eq 1). The butadienylstannanes are commonly prepared by hydrostannylation of alkynes,3-5 or addition of (phenylthio)(trimethylstannyl)cuprate to alkynes.3

A convenient method for the preparation of 4-alkoxy-8a and 4-silyloxy-1,3-butadienyl-1-lithium8 derivatives is bromine-lithium exchange with t-Butyllithium (eq 2).

Metal-halogen exchange between equimolar quantities of (E,E)-1-bromo-1-(trimethylsilyl)penta-1,3-diene and s-Butyllithium (THF-cyclohexane, -78 °C, 30 min) affords lithiated species (eq 3).9

Exchange of one bromine atom in unstable 1,4-dibromobutadiene occurs with s-BuLi (1 equiv) or t-BuLi (2 equiv) (eq 4), whereas the use of n-BuLi favors polymer formation.10 Both bromine atoms are exchanged with an excess of t-BuLi (4 equiv).

1,3-Dienyl ethers are readily lithiated at C-1 using t-BuLi (R = Me),11a s-BuLi (R = MOM),11b or n-BuLi and Potassium t-Butoxide in THF (R = Me, Ph; diene:t-BuOK:n-BuLi ratio is 1:1.04:1.10).11c The butadienyl-1-potassium formed first is subsequently transmetalated. The metalation of ethers and (E)-dienylic sulfides occurs with retention of configuration (eqs 5 and 6), while in the case of (Z)-dienylic sulfides the structure of the products depends on both reaction conditions and the S-alkyl substituent: higher temperatures and more bulky thioalkyl groups promote inversion of configuration (eq 7).11c

Higher temperatures also promote side reactions (1,4-addition of BuLi) and tar production. Treatment of butadienyl monosulfides with alkyllithium (n-, s- or t-Bu) reagents in THF in the absence of t-BuOK gives insignificant metalation even in the presence of TMEDA (N,N,N,N-Tetramethylethylenediamine). The main reaction is 1,4-addition of R2Li to the conjugated diene (eq 8). On the other hand, 1,4-bis(methylthio)buta-1,3-dienes are monolithiated with n-BuLi in THF-TMEDA mixtures at low temperature.12 When (1Z,3E)-bis-sulfides are used, lithium is introduced exclusively at the (E) double bond (eq 9).

Reactions of 1,3-Butadienyl-1-lithium Reagents.

The 1,3-butadienyl-1-lithium reagents (4-lithio-1,3-pentadiene,3,13 1-alkoxy-,11 and 1-alkylthio-1,3-butadienyl-1-lithium11c) react smoothly with a variety of electrophiles (halides, methyl thiocyanate, aldehydes, and ketones) and produce the corresponding substituted dienes (eqs 10 and 11).

Electrophilic substitution at the lithiated carbon proceeds with retention of configuration. Yields of the substituted dienes are as high as 90% for methylation and 60-75% for alkylation with higher alkyl halides and carbonyl compounds.

Lithiobutadienyl alkyl and silyl ethers are suitable intermediates in the synthesis of polyethylenic aldehydes and ketones (eq 12). These are important building blocks in natural product synthesis (polyene and macrolide antibiotics and terpenes). Starting from (E)-lithiated ethers and aldehydes or ketones, exclusively (E)-isomers are obtained.7,8 An exception is benzophenone, which gives some loss of stereochemistry.8b Yields of the dienols (dieno ketones) are 70-90%.

The condensation of lithiated dienol ethers with conjugated carbonyl compounds and the hydrolysis of the intermediate adduct leads in one pot to polyconjugated ketones. Use of the lithiated dienol ether is recommended over that of the lithiodioxolane (eq 13).8a

Reaction of 1,3-butadienyl-1-lithium with chloro ketones is used for the sequential introduction of two neighboring 1,3-butadienyl groups on a cyclohexane ring (eq 14).4,6 The silylated product undergoes thermal [5,5]-sigmatropic rearrangement to form a macrocyclic enol ether, giving cyclotetradecatrienone after hydrolysis.1

A mixed cuprate derived from a lithiodiene and n-PrC&tbond;CCu in ether-(Me2N)3P reacted with an unsaturated ketone to yield the 1,4-addition product (eq 15).5

Lithiated 1,3-butadienyl 1,4-disulfides can be alkylated or cyclized to form thiophenes, depending on reaction conditions (eq 16).12

1,3-Butadienyllithium derivatives are suitable intermediates for transmetalation reactions (eqs 17 and 18). The 1-trimethylsilyl-1,3-pentadienyl-1-lithium is transmetalated to the corresponding magnesium derivative by interaction with freshly prepared Magnesium Bromide (obtained from the reaction of Mg with BrCH2CH2Br in 3:1 ether-benzene solvent).9 The reaction of cyclopentadienyldicarbonyliron iodide with 4-bromobutadienyl-1-lithium proceeds with the retention of configuration.10

Related Reagents.

1,3-Butadienyl-2-lithium; 1,3-Butadienyl-2-magnesium Chloride; 1,3-Butadienyl-1-magnesium Chloride.

1. Angoh, A. G.; Clive, D. L. CC 1984, 534.
2. Watson, S. C.; Eastham, J. F. JOM 1967, 9, 165.
3. Piers, E.; Morton, H. E. JOC 1980, 45, 4263.
4. Wender, P. A.; Sieburth, S. McN.; Petraitis, J. J.; Singh, S. K. T 1981, 37, 3967.
5. Mori, K.; Fujioka, T. TL 1982, 23, 5443.
6. Wender, P. A.; Sieburth, S. McN. TL 1981, 22, 2471.
7. Wollenberg, R. H. TL 1978, 717.
8. (a) Duhamel, L.; Ancel, J.-E. T 1992, 48, 9237. (b) Contreras, B.; Duhamel, L.; Ple, G. SC 1990, 20, 2983.
9. Wrobel, J. E.; Ganem, B. JOC 1983, 48, 3761.
10. Ferede, R.; Noble, M.; Cordes, A. W.; Allison, N. T.; Lay, J., Jr. JOM 1988, 339, 1.
11. (a) Soderquist, J. A.; Hassner, A. JACS 1980, 102, 1577. (b) McDougal, P. G.; Rico, J. G. JOC 1987, 52, 4817. (c) Everhardus, R. H.; Gräfing, R.; Brandsma, L. RTC 1978, 97, 69.
12. Everhardus, R. H.; Eeuwhorst, H. G.; Brandsma, L. CC 1977, 801.
13. Burke, S. D.; Powner, T. H.; Kageyama, M. TL 1983, 24, 4529.

Viesturs Lūsis

Latvian Institute of Organic Synthesis, Riga, Latvia

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