Propargylic silanes, synthesis

Table 9.28 Synthesis of propargylic silanes by SN2 displacement of propargylic sulfmates.

Y. Liu, G. Asymmetric synthesis of a-amino allyl, benzyl, and propargyl silanes by metalation and rearrangement. Org. Lett. 2003, 5, 1859-1861. 

For a review on intramolecular reactions of allylic and propargylic silanes, see D. Schinzer, Synthesis, 1988,4, 263. 

This reaction type is useful for the synthesis of tropane-like azabicycles (equations 94 and 95). Allyl-and propargyl-silanes are excellent nucleophiles in this process.Enone (125) is probably first transformed into an enol ether (c/. equation 70) before it cyclizes to the homotropane skeleton, which is eventually isolated as a mixture of enone (126) and chloride (127). 

Intramolecular Addition Reactions of Allylic and Propargylic Silanes" Schinzer. D. Synthesis. 1988, 263. 

For some reviews about S akurai reaction, see (a) Y. Yamamoto, N. Sasaki in Chemical bonds—better ways to make them and break them (I. Bernal, Ed.). Elsevier, Amsterdam, The Netherlands, 1989, pp. 363 441. The stereochemistry of the Sakurai reaction, (b) D. Schinzer, Synthesis 1988, 263-273. Intramolecular addition reactions of allylic and propargylic silanes, (c) Y. Yamamoto, N. Asao, Chem Rev. 1993, 93, 2207-2293. Selective reactions using allylic metals. 

Reactivity. 3-Trimethylsilyl-l-prop)nie is the simplest of the propargylic silanes, which are convenient reagents in organic synthesis. ... 

Substituted allenes are obtained from the reaction of propargyl silanes (prepared from lithium alkynes and trimethylsilylmethyl chloride ) and electrophiles. An exocyclic allene is produced when this reaction involves ring closure, a method which has been applied in a biomimetic steroid synthesis (Scheme 16). ° If the corresponding trimethylsilylalkyne is used a D-homosteroid system is obtained. ... 

Allenyllithium reagents are commonly prepared through lithiation of propargylic halides or by deprotonation of alkynes or certain allenes (Eq. 9.1). Lithiated allenes often serve as precursors to stable allenylmetal compounds such as stannanes or silanes. They can also be employed for the in situ synthesis of allenylzinc, -titanium and -boronate compounds, which can be further transformed to substitution products not accessible from their allenyllithio precursors. 

Table 9.29 Synthesis of allenylsilanes from propargylic 1,3-b/s-silanes.

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