Chlorotriphenylstannane

Ph3SnCl

[639-58-7]  · C18H15ClSn  · Chlorotriphenylstannane  · (MW 385.49)

(precursor of alkyl-, allyl-, and allenyltriphenylstannanes for stereo- and regioselective C-C bond formation;1,4 triphenyltin enolates for diastereoselective aldol condensation5,6 and for avoiding polyalkylation11)

Alternate Name: triphenyltin chloride.

Physical Data: mp 108 °C (dec); bp 240 °C/13.5 mmHg.

Solubility: sol THF, CH2Cl2; slightly sol ether.

Form Supplied in: white solid; widely available.

Handling, Storage, and Precautions: normally, commercially available chlorotriphenylstannane may be used as received. The reagent is air stable, but is decomposed by moisture. The reagent is toxic and should be handled with gloves. Use in a fume hood.

Introduction.

As mentioned in the entry for Tri-n-butylchlorostannane, Ph3SnCl is a useful starting material for the synthesis of other triphenyltin reagents such as Triphenylstannane, cyanotriphenylstannane, triphenyltin methoxide, triphenyltin azide, and triphenylstannyllithium, etc.

Organotriphenyltins via Transmetalation.

The reaction of Ph3SnCl with allylic anions substituted with heteroatoms such as sulfur and oxygen affords allylic triphenylstannanes having heteroatoms at the g-position. The subsequent reaction of the allylic tin derivatives with aldehydes in the presence of Boron Trifluoride Etherate give the syn-g-adduct predominantly (eq 1).1 In general, the reaction with aldehydes is carried out without isolating the intermediate allylic stannanes; thus treatment of the allylic anion with Ph3SnCl, followed by addition of aldehydes/BF3.OEt2, produces the homoallyl alcohols. The g-regioselectivity is perfect, but the syn diastereoselectivity is between 90 and 70% de.

Chlorotributylstannane may be used instead of Ph3SnCl, and similar levels of diastereoselectivity are obtained. However, the use of triphenylstannane derivatives is recommended due to their lower toxicity and easier separation of the triphenylstannyl residue. Lithiated 1,3-dithianes react with chlorotrialkyl- or chlorotriphenylstannanes to form the corresponding 1,3-dithian-2-ylstannyl compounds.2 Cyclohexyl- and cyclohexenyltriphenylstannanes are prepared from the corresponding Grignard reagents with Ph3SnCl.3 The reaction of allenylmagnesium bromides with Ph3SnCl and Sodium Iodide gives allenyltriphenylstannanes, which react regioselectively with a,b-enones in the presence of Titanium(IV) Chloride to afford the conjugate propargylation products in good yields (eq 2).4 Propargylation of nitroalkenes takes place with allenyltriphenylstannanes in the presence of TiCl4.4

Triphenylstannyl Enolates.

Triphenylstannyl enolates, prepared in situ by reaction of lithium enolates with Ph3SnCl, react with aldehydes at -78 °C to afford mainly syn products, irrespective of the geometry of the enolate (eq 3). Assistance with a Lewis acid is not necessary.5 The corresponding tributylstannyl and trimethylstannyl enolates, prepared in a similar manner, react with benzaldehyde to give a ca. 1:1 mixture of syn and anti adducts. On the other hand, the reaction of the enol stannanes of cyclohexanone or propiophenone, prepared from enol acetates and trimethyl- or tributyltin methoxide and isolated by distillation, with aldehydes under kinetic conditions (-78 °C) give predominantly the anti aldols, with diastereoselectivity as high as 95:5 being achieved (eq 4).6

At higher temperatures (45 °C), mainly syn selectivity is observed. Lithium Chloride, present in the in situ generated tin enolate, plays an important role in producing the syn diastereoselectivity in these reactions, as has been established for the reactions of germanium enolates.7 However, the triphenylstannyl or trimethylstannyl enolate of 4-thianone, prepared in situ from the corresponding lithium enolate and Ph3SnCl or Me3SnCl, reacts with 2-methylpropanal to form the anti aldol predominantly.8

a-Lithiostannylalkylphosphonates react with aldehydes with the complete elimination of the organotin moiety (eq 5).9 The stereoselective formation of the (E)- or (Z)-a-alkenylphosphonates is dependent on the tin substituent; Ph3Sn derivatives produce the (Z)-alkene predominantly (with 60-97% stereoselectivity), whereas Bu3Sn analogs afford the (E)-alkene with 80-97% selectivity.

Although the alkylation of lithium enolates is often accompanied by undesired polyalkylation, it is avoided by using tin enolates.10 The polyalkylation is a major drawback in the alkylation of enolates formed by cuprate conjugate addition to enones, but the use of trialkylstannyl and triphenylstannyl enolates prevents polyalkylation and enhances the yield of the desired monoalkylation product.11


1. Yamamoto, Y.; Saito, Y.; Maruyama, K. TL 1982, 23, 4959.
2. Klaveness, J.; Rise, F.; Undheim, K. JOM 1986, 303, 189.
3. Fish, R. H.; Broline, B. M. JOM 1978, 159, 255.
4. Haruta, J.; Nishi, K.; Matsuda, S.; Akai, S.; Tamura, Y.; Kita, Y. JOC 1990, 55, 4853.
5. Yamamoto, Y.; Yatagai, H.; Maruyama, K. CC 1981, 162.
6. Labadie, S. S.; Stille, J. K. T 1984, 40, 2329.
7. Yamamoto, Y.; Yamada, J. CC 1988, 802.
8. Hayashi, T. TL 1991, 32, 5369.
9. Mimouni, N.; About-Jaudet, E.; Collignon, N.; Savignac, Ph. SC 1991, 21, 2341.
10. (a) Tardella, P. A. TL 1969, 1117. (b) Pereyre, M.; Odic, Y. TL 1969, 505.
11. (a) Nishiyama, H.; Sakuta, K.; Itoh, K. TL 1984, 25, 2487. (b) Suzuki, M.; Yanagisawa, A.; Noyori, R. JACS 1985, 107, 3348. (c) Yamamoto, Y.; Yatagai, H.; Maruyama, K. Rev. Silicon, Germanium, Tin, Lead Compd. 1986, 9, 25.

Yoshinori Yamamoto

Tohoku University, Sendai, Japan



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