2-Trimethylsilylmethyl-2-propen-1-ol1

[81302-80-9]  · C7H16OSi  · 2-Trimethylsilylmethyl-2-propen-1-ol  · (MW 144.32)

(derivatives function as trimethylenemethane (TMM) precursors and undergo cyclopentannulation reactions; methylenecyclopentanes; 2-acetoxymethyl-3-trimethylsilylpropene;2 [3 + 2] annulation;3 three-carbon condensative expansion;4 cyclocontraction-spiroannulation5)

Alternate Names: 2-(hydroxymethyl)-3-trimethylsilylpropene; 2-(hydroxymethyl)-2-propenyltrimethylsilane; (hydroxymethyl)allyl trimethylsilane; 2-(trimethylsilylmethyl)allyl alcohol.

Physical Data: bp 54-56 °C/2 mmHg; n20D 1.454; d 0.861 g cm-3; fp 71 °C.

Solubility: insol water; sol all organic liquids.

Form Supplied in: liquid, 90% pure; remainder of the mixture (approx. 10%) is 3-trimethylsilyl-2-methyl-2-propen-1-ol or 3-trimethylsilylmethyl-2-propen-1-ol.

Preparative Method: prepared in four steps from methallyl alcohol. The synthesis begins with the metalation with n-Butyllithium (2 equiv) producing the dianion which is bis-silylated by trapping with Chlorotrimethylsilane to generate the allylsilane. The TMS ether is subsequently removed by hydrolysis (eq 1). The primary allylic alcohol serves as a precursor to more functionalized reagents.

Useful derivatives of the alcohol are the primary allylic chloride, mesylate, and acetate. These are easily prepared in a short number of steps as shown (eq 2) or by functionalization of the primary allylic alcohol.

Purification: by distillation under reduced pressure.

Handling, Storage, and Precautions: flammable liquid; irritant; store at 0-4 °C.

Introduction.

The title allylsilane reagent has been employed as a conjunctive reagent which is considered to be a synthetic equivalent of a zwitterionic, bifunctional compound possessing a nucleophilic allylic anion synthon and an electrophilic cation synthon in the same molecule (1).

[3 + 2] Annulations.

The primary allylic halide 2-Chloromethyl-3-trimethylsilyl-1-propene or the mesylate derived from the corresponding alcohol behaves as a bifunctional reagent possessing both nucleophilic and electrophilic reaction centers. For example, they have been shown to participate in [3 + 2] carbon annulations for the construction of methylenecyclopentanes. The reaction proceeds through a Lewis acid-promoted conjugate addition (Sakurai reaction) followed by an internal alkylation of the derived ketone enolate (eq 3).

In a related study, the annulation is combined with a ring expansion reaction. The reaction utilizes a b-keto sulfone as the two-carbon component along with an allylic mesylate as the bifunctional reagent. The alkylation/cyclization process is outlined in eq 4. The subsequent ring expansion appears to be a general process except for cases involving fused six- and seven-membered ring systems (eq 5).

Methylenecyclopentane Annulation.

The acylated derivative 2-acetyloxymethyl-3-trimethylsilylpropene is known to be an effective three-carbon component in cyclopentane annulations. It has been demonstrated that 2-acetoxymethylallyltrimethylsilane adds to a variety of electron-deficient alkenes in the presence of a catalytic amount of Tetrakis(triphenylphosphine)palladium(0) and 1,2-Bis(diphenylphosphino)ethane to produce methylenecyclopentanes (eqs 6-8).

Cyclocontraction-Spiroannulation.

The mesylate derivative of 2-hydroxymethyl-3-trimethylsilylpropene participates in an interesting annulation reaction involving a b-keto sulfone as the two-carbon component (eq 9).

The reaction is thought to involve a pinacol-type rearrangement in which the phenylsulfonyl group serves as a leaving group in the presence of a Lewis acid (eq 10).

Related Reagents.

3-Acetoxy-2-trimethylsilylmethyl-1-propene; 3-Iodo-2-trimethylsilylmethyl-1-propene.


1. Trost, B. M.; Chan, D. M. T.; Nanninga, T. N. OS 1984, 62, 58.
2. Trost, B. M.; Chan, D. M. T. JACS 1979, 101, 6429.
3. Knapp, S.; O'Connor, U.; Mobilio, D. TL 1980, 21, 4557.
4. Trost, B. M.; Vincent, J. E. JACS 1980, 102, 5680.
5. Trost, B. M.; Adams, B. R. JACS 1983, 105, 4849.

James S. Panek & Pier F. Cirillo

Boston University, MA, USA



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