· (MW 391.08)
(widely used allylating agent as an allyl anion equivalent directly or by transmetalating to other allylmetals,2,3 radical chain transfer reagent, and source of allyl radical4)
Alternate Names: allyltriphenyltin; (2-propenyl)triphenylstan-nane.
Physical Data: mp 73-74 °C (recryst. from ligroin).5
Solubility: sol THF, methylene chloride, chloroform, and benzene.
Form Supplied in: white solid in over 97% purity (microanalysis).
Analysis of Reagent Purity: CH microanalysis, IR,6 1H,7 or 13C NMR spectroscopy.
Handling, Storage, and Precautions: poison by intravenous route; ivn-mus LD50: 100 mg kg-1;8 no significant reactivity with aqueous systems. Use in a fume hood.
Generation of Allyllithium.
Allyllithium may be generated effectively upon treatment of allyltriphenyltin with Phenyllithium in ether.2,3 The resulting allyllithium may be further converted into allylboronate complexes upon treatment with trialkylboranes.3
Lewis Acid-Mediated Allylation Reactions.
Although allyltriphenyltin has been extensively used as a reagent for nucleophilic allylation under Lewis acid catalysis,1 it does not appear to offer a particular advantage in terms of yield and reactivity when compared with the same reaction with Allyltributylstannane (e.g. eq 1).9
A number of highly stereoselective allylation reactions have been developed which involve treatment of Lewis acid-chelated a- or b-heteroatom substituted aldehydes with allytriphenyltin. While a-benzyloxy aldehydes undergo allylation favoring anti adducts in the presence of Tin(IV) Chloride (eq 2), a-thiomethyl aldehydes produce allylated products with high syn/anti ratios (typically, 94-97:6-3) in excellent yield.10 b-Alkoxy aldehydes give rise to allyl adducts generally with high anti selectivity (e.g. eq 3).10 Variations in anti/syn ratio caused by the different protecting groups as well as Lewis acids have been rationalized on the basis of the conformational preferences of the chelated a-alkoxy
aldehydes.11a The highly 1,3-diastereoselective allylation reaction has been applied to the total synthesis of (-)-colletol.11b
An allyl group is added stereoselectively to chiral dioxane acetals upon reaction with allyltriphenyltin in the presence of Titanium(IV) Chloride/Titanium Tetraisopropoxide, although the use of allyltributyltin in place of allyltriphenyltin gives better diastereoselectivity (eq 4).12 A TiCl4 catalyzed Michael-type addition of an allyl group onto 1-nitroalkadienes followed by addition of Triethylamine provides a nitrile oxide equivalent which undergoes intramolecular 1,3-dipolar cycloadditions to give isoxazolines (eq 5).13 A novel [3 + 2] cycloaddition involving allylstannanes and a,b-unsaturated acyliron complexes has also been reported14 (see trans-Cinnamyltributylstannane).
Allyltriphenyltin can serve as an excellent radical chain transfer agent as well as a source of an allylic radical, as shown in eq 6.4 Interestingly, when Triphenylstannane is used instead of allyltriphenyltin, a mixture of a- and b-methylcepham is obtained (eq 7).4
- 1. Yamamoto, Y.; Asao, N. CRV 1993, 93, 2207.
- 2. Seyferth, D.; Weiner, M. A. JOC 1961, 26, 4797.
- 3. Yamamoto, Y.; Yatagai, H.; Maruyama, K. JACS 1981, 103, 1969.
- 4. Baldwin, J. E.; Adlington, R. M.; Kang, T. W.; Lee. E.; Schofield, C. J. CC 1987, 104. See also Curran, D. P.; van Elburg, P. A.; Giese, B.; Gilges, S. TL 1990, 31, 2861.
- 5. Seyferth, D.; Weiner, M. A. OSC 1973, 5, 452.
- 6. Henry, M. C.; Noltes, J. G. JACS 1960, 82, 555.
- 7. Kawakami, K.; Kuivila, H. G. JOC 1969, 34, 1502.
- 8. Lewis, R. J., Sr. Sax's Dangerous Properties of Industrial Materials, 8th ed.; Van Nostrand Reinhold: New York; 1992; Vol. II, p 122.
- 9. Ohkata, K.; Ishimaru, K.; Lee, Y.-g.; Akiba, K. CL 1990, 1725. See also Uno, H. JOC 1986, 51, 350. Hashimoto, Y.; Sugumi, H.; Okauchi, T.; Mukaiyama, T. CL 1987, 1695. Hayashi, Y.; Mukaiyama, T. CL 1987, 1811.
- 10. Shimagaki, M; Takubo, H.; Oishi, T. TL 1985, 26, 6235. See also Sato, T.; Otera, J.; Nozaki, H. JOC 1990, 55, 6116.
- 11. (a) Keck, G. E.; Castellino, S.; Wiley, M. R. JOC 1986, 51, 5478. (b) Keck, G. E.; Murry, J. A. JOC 1991, 56, 6606.
- 12. Denmark, S. E.; Almstead, N. G. JOC 1991, 56, 6485. See also Yamamoto, Y.; Nishii, S.; Yamada, J. JACS 1986, 108, 7116.
- 13. Uno, H.; Watanabe, N.; Fujiki, S.; Suzuki, H. S 1987, 471.
- 14. Herndon, J. W. JACS 1987, 109, 3165. Herndon, J. W.; Wu, C.; Harp, J. J. OM 1990, 9, 3157.
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