Tetrahydropyranyloxy-1-trimethylsilyl- 1-propyne

Miscellaneous Reactions. 2,4,6,8-Tetraethenyl-2,4,6,8-tetra-methylcyclotetrasiloxane acts as a chelating ligand for a bimetallic nickel(O) complex, similar to Karstedt s catalyst. The combination of and tetramethylcyclotetrasiloxane in the presence of Karstedt s catalyst cross-links the two tetramers to prepare a platinum-containing glass.Additionally, Bennetau and Boileau have functionalized with CgFnI under ultrasonic irradiation conditions to provide tetra(perfluorooctyl)-substituted D4 after reductive cleavage of the iodide with tributyltin hydride.  

Preparative Methods from 2-propynol via tetrahydropyranyl ether formation, deprotonation, and trimethylsilylation from 3-trimethylsilylpropynol via tetrahydropyranyl ether forma tion.  

Handling, Storage, and Precautions store in the absence of air and moisture. 

Alkoxypropargylation. The ambident character of the propargylic anion, which may be in equihbrium with the aUenic form, is responsible for its limited use in synthesis. In general the structure and reactivity of the ambident anion depend on the nature of the substrate, the counter cation, and the solvent. There is also an erythro-threo stereoselectivity problem when alkylated propargylic anions react with aldehydes or unsymmetrical ketones. In contrast, the zinc and titanium reagents derived from the title compound possess the allenic structure and, upon reaction with aldehydes, lead almost exclusively to the )8-acetylenic alcohol (eq 1), presumably by a chelate transition state (Sei process). The reaction also leads preferentially to the erythro diastereomer. The stereoselectivity is highest with titanium as the metal and THE as the solvent.  

Whereas the titanium reagent is not reactive towards ketones, the zinc derivative has been found to react even with sterically encumbered ketones, such as 17-keto steroids, to yield the )3-acetylenic alcohol in good yield 15%)  

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P-Acetylenic alcohols (11, 378). The propargyltitanium reagent derived from 1-trimethylsilyl-3-(tetrahydropyranyloxy)propyne (1) reacts with crotonaldehydes to afford the P-acetylenic alcohol 2 with high stereoselectivity. This alcohol was used in a stcr-eocontrolled synthesis of the natural antibiotic ( )-asperlin (6). 

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