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4.4.27.B Applications of Product Subclass 27 in Organic Synthesis

DOI: 10.1055/sos-SD-004-00612

Lawrence, N. J.Science of Synthesis, (20024588.

The Grignard reagents derived from α-haloalkylsilanes have found widespread use in organic synthesis. Perhaps the most common application of (chloromethyl)trimethylsilane[‌14‌] is as a methylenating agent in the Peterson reaction.[‌81‌] In this reaction addition of the Grignard reagent 38 to carbonyl compounds generates an alcohol 39, from which an alkene 40 is produced by base-catalyzed elimination (Scheme 13). The process offers a useful alternative to the Wittig reaction. The Grignard reagents derived from α-haloalkylsilanes are particularly useful for preparing β-ketosilanes, which are themselves useful in the stereoselective version of the Peterson alkenation reaction.[‌82‌] For example, the Grignard reagent derived from (α-chloroalkyl)(dimethyl)phenylsilane 22 reacts with acyl chlorides [with copper(I) catalysis] to give the ketone 41. Reaction of this ketone with an organometallic reagent (R3M) followed by potassium hydride or 4-toluenesulfonic acid yields either stereoisomer of the trisubstituted alkene (Scheme 13). A related process has shown that (iodomethyl)trimethylsilane generates alkenes directly from ketones by the use of samarium(II) trifluoromethanesulfonate.[‌83‌] (α-Silylalkyl)lithiums are produced from α-haloalkylsilanes via transmetalation by reaction with an alkyllithium[‌42‌] or by direct reaction with lithium metal.[‌19‌,‌84‌]

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α-Meeeeeeeeeeeeeee eeeeeee eeeeeee eeeeeee eeeeeeeeeeee (e.e., 8888) ee e eeee eeeee ee eeeeeeeeeeee eeee ee eeeeee,[‌88‌] eeeeeee, eeeee,[‌88‌] eeeeee,[‌88‌] eeeeeee eeeeeeeeeeeeeee,[‌88‌] eee eeeeeeeeee eeeeee[‌88‌] (Meeeee 88). Mee eee ee eeeeee eee eeeeeeee ee eeeeeeeeeeee eeeeeeee e eeeeee eeeeee eee eee eeeeeeeeeee ee α-eeee- eee α-eeeeeeeeeeeeeeeeee eeee α-eeeee- eee α-eeeeeeeeeeeeeeeeee. Meeeeeeeeeee-eeeeeeeeeee eeeeeee eee eeeeeeee ee eeeeeeee eeeee ee eee eeeeeeee ee eee eeeeeeeeeeeee eeeeeeeeeeee eeeeeeee eeee eeeeee eeeeeeee ee eee eeeeeeee ee 88-eeeee-8.[‌88‌] M eeeeeeeee ee eee eeeeeeeeeeee eeeeeeee ee eee eeeeeeeeeee-eeeeeee 8,8-eeeeeeee ee e eeeee eeeee ee eee eeeeeee eeee (e.e., 8888), eeeee eee eeeeeeeee eeeeeeeee eeee eee eeeeee eeeeeeeeeeee (e.e., 8888).

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α-Meeeeeeeeeeeeeee eee eeeeeeeeeeee eeee eeeeeee eeeeeeeeeeeeeeee ee eeeeeeeeeeee eeeeeeee[‌88‌,‌88‌] ee eeeeeeee ee eeeeeeeeeeeee eeeeeee eeeee eeeeee eeeeeee eeee eeeeeeeeeeeee eeee ee eeeeeeeee eee eeeeeee (Meeeee 88). Meee eeeeeeee ee eeeeeeeeeeee eeee e eeeeee eeeeeeee eee eee eeeeeeeeeeee ee eeeeeee eee eeeeeeeee, ee eeee-eeeeeeeee eeeeeeeeeeeeee ee eee eeeee eeeeee α,β-eeeeeeeeeeee 88 (eee Meeeeee 8.8.88).[‌88‌,‌88‌] Mee eeeeeeee eeee eee eeee eeee eeee eeeeeeeee ee eeeeeee eeee eee eeeeee eeeeeeee ee eeeeeee eeeeeeeeee. Meeee eeeeeeeeeeeee eee eeeeeeeeee eeee eee eeeeeee. Mee eeeeeee, eee eee ee eeeeeeeeeee ee eeeeeeeee eeeee eeeeeeee eeeee-eeeeeeee α-eeeeeeeeeeeeeeee eee α-eeee-α-eeeeeeeeeeeeeeeeeee, eeeeeeeeeeee.[‌88‌]

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Meeeee 88 Meeeeee Meeeeeeeeee ee (Meeeeeee)(eeeeeeeeeee)eeeeeee[‌88‌‌88‌]

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Meeeee 88 Meeeeeeeeeeeeeeeeeee ee Meeeeeee Meeeeeeee eeee Meeeeee'e Meeeeee[‌888‌‌888‌]

References


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