3-Trimethylsilyl-2-propen-1-yl Acetate

(1; R1 = H, R2 = (E)-SiMe3)

[86422-21-1]  · C8H16O2Si  · 3-Trimethylsilyl-2-propen-1-yl Acetate  · (MW 172.33) (2; R1 = H, R2 = (Z)-SiMe3)

[86422-22-2] (E + Z)

[80401-14-5] (3; R1 = SiMe3, R2 = H)


(preparation of vinylsilanes via the corresponding allylmetal complexes;1 oxygenated allylsilane reagents for nucleophilic addition and substitution reactions2)

Preparative Methods: (i) from 3-trimethylsilyl-2-propyn-1-ol by reduction (Sodium Bis(2-methoxyethoxy)aluminum Hydride (Red-Al), 70%)3 and acetylation (Acetyl Chloride, Pyridine, 78%);4 (ii) from 3-trimethylsilyl-2-propyn-1-ol by reduction (P-2 Raney Nickel, H2, 86%)5 and acetylation; (iii) from allyloxytrimethylsilane by a metalation-rearrangement sequence (t-Butyllithium, 90%)2a,6 and acetylation (Acetic Anhydride, Triethylamine, 76%).2a

Handling, Storage, and Precautions: use in a fume hood.

Preparation of Vinylsilanes.

Both (E)- and (Z)-3-trimethylsilyl-2-propen-1-yl acetates (1 and 2), together with their allylic isomer (3) (1-trimethylsilyl-2-propen-1-yl acetate) are useful reagents for the formation of vinylsilanes by way of transition metal-catalyzed allylic alkylations. Reaction of the p-allylpalladium intermediate generated from (1)-(3) with several types of nucleophiles has been studied.4,7 In general, these alkylations exhibit high regioselectivity, with reaction occurring at the position g to silicon. Diethyl Malonate sodium enolate reacts with either (2) or (3) in the presence of Pd0 to give alkylated products in good yields and favoring the (Z)-vinylsilane isomer (eq 1).1 Cyclohexanone enamine participates in the alkylation reaction, giving the (E)-vinylsilane as the sole product (eq 2).1 Although lithium enolates are problematic, addition of tri-n-butyltin trifluoroacetate allows product formation in good yield (eq 3).8

Other metals besides palladium are also effective.9 Reaction of the cationic allyltetracarbonyliron complex derived from (1) or (2) with silyl enol ethers, O-silyl ketene acetals, or allylstannanes, followed by oxidative decomplexation, gives the vinylsilane products.10 The process was shown to occur with near complete retention of stereochemistry (cf. eqs 4 and 5).10

Nucleophilic Addition and Substitution Reactions.

Allylsilane (3) has been shown to undergo conjugate addition to enones in the presence of Tetra-n-butylammonium Fluoride (eq 6).2a The reaction demonstrates high regioselectivity, as no products arising from 1,2-addition to the enone or attack at the g-position of the allylsilane were isolated. Stereoselective C-glycosidation can be effected by reaction of allylsilane (3) with D-mannopyranoside derivatives in the presence of Boron Trifluoride Etherate (eq 7).2b The a-C-glycoside arises from axial addition to the pyranoside oxonium ion.

Related Reagents.

Allyltrimethylsilane; 3-Bromo-1-trimethylsilyl-1-propene; 1-Pyrrolidino-1-cyclohexene; Tetrakis(triphenylphosphine)palladium(0); Trimethylsilylallyllithium.

1. Hirao, T.; Enda, J.; Ohshiro, Y.; Agawa, T. TL 1981, 22, 3079.
2. (a) Panek, J. S.; Sparks, M. A. TL 1987, 28, 4649. (b) Panek, J. S.; Sparks, M. A. JOC 1989, 54, 2034. (c) Aicher, T. D.; Buszek, K. R.; Fang, F. G.; Forsyth, C. J.; Jung, S. H.; Kishi, Y.; Scola, P. M. TL 1992, 33, 1549.
3. Jones, T. K.; Denmark, S. E. OSC 1990, 7, 524.
4. Trost, B. M.; Self, C. R. JACS 1983, 105, 5942.
5. Hiemstra, H.; Klaver, W. J.; Speckamp, W. N. RTC 1986, 105, 299.
6. Danheiser, R. L.; Fink, D. M.; Okano, K.; Tsai, Y.; Szczepanski, S. W. OS 1988, 66, 14.
7. Mori, M.; Isono, N.; Kaneta, N.; Shibasaki, M. JOC 1993, 58, 2972.
8. Trost, B. M.; Self, C. R. JOC 1984, 49, 468.
9. For use of Mo(CO)6, see: Trost, B. M.; Lautens, M. OM 1983, 2, 1687.
10. Gajda, C.; Green, J. R. SL 1992, 973.

David L. Clark

University of California, Berkeley, CA, USA

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