1-Ethoxy-4-tributylstannyl-1,3-butadiene1

[66876-05-9]  · C18H27OSn  · 1-Ethoxy-4-tributylstannyl-1,3-butadiene  · (MW 386.91)

(reagent for the four-carbon homologation of aldehydes and ketones to dienals)

Physical Data: bp 120-130 °C/0.3 mmHg.2

Solubility: sol THF.

Preparative Methods: prepared as a mixture of (E) and (Z) isomers by the hydrostannation of 1-ethoxy-1-buten-3-yne with one equivalent of Tri-n-butylstannane and catalytic Azobisisobutyronitrile.2

Purification: purified by distillation.2

Handling, Storage, and Precautions: organostannane reagents are potentially toxic;3 their preparation and use must therefore be conducted wearing appropriate protective clothing in a well ventilated hood. The reagent should be stored under an inert atmosphere and protected from light and moisture.

Transmetalation.

Transmetalation of 1-ethoxy-4-tributylstannyl-1,3-butadiene (1) with one equivalent of n-Butyllithium at -78 °C proceeds smoothly to afford 1-lithio-4-ethoxy-1,3-butadiene (2).2 This reagent reacts with aldehydes and ketones to yield the expected 1,2-adducts. Treatment of the resulting enol ethers with catalytic acid promotes the rearrangement to afford dienal products2,4 (eq 1).4a Substrates which are sensitive to acidic environments can be converted to dieneals by treatment of the corresponding allylic mesylate with Triethylamine (eq 2).5 This overall procedure provides (E,E)-dieneals in high geometric purity from aldehydes. Condensation of (2) with ketones affords mixtures of (E,E) and (E,Z) products.2 Consequently, this reagent is of less synthetic utility for the homologation of ketones to geometrically pure (E,E)-dienals.

The iterative condensation of (2) provides an efficient method for the preparation of (E)-polyenals with high isomeric purity.6,7 This approach was found to be superior to either the Wittig-Horner or Corey's lithio-N,N-dimethylhydrazone homologation procedures for the construction of geometrically pure hexenal (3) (eq 3).6,7


1. For recent reviews and collected papers on the chemistry of organostannanes, see: (a) Mitchell, T. N. S 1992, 803. (b) Pereyre, M.; Quintard, J. R.; Rhan, A. Tin in Organic Synthesis; Butterworths: London, 1987. (c) Yamamoto, Y. T 1989, 45, 36. (d) Chemistry of Tin; Harrison, P. G., Ed.; Chapman & Hall: New York, 1989. (e) Stille, J. K. AG(E) 1986, 25, 508.
2. Wollenberg, R. H. TL 1978, 19, 717.
3. (a) Snoeij, N. J.; Penninks, A. H.; Seinen, W. Environ. Res. 1987, 44, 335. (b) Chang, L. J. Toxicol. Sci. 1990, 15 (Suppl. 4), 125.
4. (a) Mori, A.; Arai, I.; Yamamoto, H. T 1986, 42, 6447. (b) Wilcox, C. S.; Suh, H. JACS 1988, 110, 470. (c) Arai, Y.; Shimoji, K.; Konno, M.; Konishi, Y.; Okuyama, S.; Iguchi, S.; Hayashi, M.; Miyamoto, T.; Toda, M. JMC 1983, 26, 72. (d) Patel, P.; Pattenden, G. TL 1985, 26, 4789.
5. Corey, E. J.; Clark, D. A.; Goto, G.; Marfat, A.; Mioskowski, C.; Samuelsson, B.; Hammarström, S. JACS 1980, 102, 1436.
6. McGarvy, G. J.; Williams, J. M.; Hiner, R. N.; Matsubara, Y. Oh, T. JACS 1986, 108, 4943.
7. Williams, J. M.; McGarvey, G. J. TL 1985, 26, 4891.

Alfred P. Spada

Rhône-Poulenc Rorer Central Research, Collegeville, PA, USA



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