Preparation of monosilyl acetals from esters via iBu2AlH reduction and trapping with N-(trimethylsilyl)imidazole. Addition of allyltrimethylsilane to yield homoallylic alcohols or ethers

Dalibor Sames, Yunqi Liu, Lynn DeYoung, Robin L Polt

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26 Citations (Scopus)

Abstract

Alkyl esters were reduced with iBu2AlH or a 1:1 mixture of iBu2AlH and iBu3Al (iBu2AlH·iBu3Al or iBu5Al2H), followed by trapping of the resulting tetrahedral intermediate with TMS-imidazole to produce monosilyl acetals. Reaction of the mixed acetals with allyltrimethylsilane in the presence of Lewis acids (Hosomi-Sakurai reaction) generated homoallylic alcohols or ethers selectively, depending on the substitution of the monosilyl acetal. TMS methoxy acetals (MeO-CH-OTMS) and TMS ethoxy acetals bearing additional complexing groups such as MeO- or Ph2C=N- provided alcohols with 1.5:1-9:1 threoselectivity, while simple TMS ethoxy acetals provided only ethyl ethers as products. The monosilyl acetal configuration was easily epimerized or racemized, and the configuration of the Hosomi-Sakurai product was apparently independent of the initial monosilyl acetal reactant configuration.

Original languageEnglish (US)
Pages (from-to)2153-2159
Number of pages7
JournalJournal of Organic Chemistry
Volume60
Issue number7
StatePublished - 1995

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Acetals
Ethers
Esters
Alcohols
Ethyl Ethers
Bearings (structural)
Lewis Acids
imidazole
allyltrimethylsilane
Substitution reactions

ASJC Scopus subject areas

  • Organic Chemistry

Cite this

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title = "Preparation of monosilyl acetals from esters via iBu2AlH reduction and trapping with N-(trimethylsilyl)imidazole. Addition of allyltrimethylsilane to yield homoallylic alcohols or ethers",
abstract = "Alkyl esters were reduced with iBu2AlH or a 1:1 mixture of iBu2AlH and iBu3Al (iBu2AlH·iBu3Al or iBu5Al2H), followed by trapping of the resulting tetrahedral intermediate with TMS-imidazole to produce monosilyl acetals. Reaction of the mixed acetals with allyltrimethylsilane in the presence of Lewis acids (Hosomi-Sakurai reaction) generated homoallylic alcohols or ethers selectively, depending on the substitution of the monosilyl acetal. TMS methoxy acetals (MeO-CH-OTMS) and TMS ethoxy acetals bearing additional complexing groups such as MeO- or Ph2C=N- provided alcohols with 1.5:1-9:1 threoselectivity, while simple TMS ethoxy acetals provided only ethyl ethers as products. The monosilyl acetal configuration was easily epimerized or racemized, and the configuration of the Hosomi-Sakurai product was apparently independent of the initial monosilyl acetal reactant configuration.",
author = "Dalibor Sames and Yunqi Liu and Lynn DeYoung and Polt, {Robin L}",
year = "1995",
language = "English (US)",
volume = "60",
pages = "2153--2159",
journal = "Journal of Organic Chemistry",
issn = "0022-3263",
publisher = "American Chemical Society",
number = "7",

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TY - JOUR

T1 - Preparation of monosilyl acetals from esters via iBu2AlH reduction and trapping with N-(trimethylsilyl)imidazole. Addition of allyltrimethylsilane to yield homoallylic alcohols or ethers

AU - Sames, Dalibor

AU - Liu, Yunqi

AU - DeYoung, Lynn

AU - Polt, Robin L

PY - 1995

Y1 - 1995

N2 - Alkyl esters were reduced with iBu2AlH or a 1:1 mixture of iBu2AlH and iBu3Al (iBu2AlH·iBu3Al or iBu5Al2H), followed by trapping of the resulting tetrahedral intermediate with TMS-imidazole to produce monosilyl acetals. Reaction of the mixed acetals with allyltrimethylsilane in the presence of Lewis acids (Hosomi-Sakurai reaction) generated homoallylic alcohols or ethers selectively, depending on the substitution of the monosilyl acetal. TMS methoxy acetals (MeO-CH-OTMS) and TMS ethoxy acetals bearing additional complexing groups such as MeO- or Ph2C=N- provided alcohols with 1.5:1-9:1 threoselectivity, while simple TMS ethoxy acetals provided only ethyl ethers as products. The monosilyl acetal configuration was easily epimerized or racemized, and the configuration of the Hosomi-Sakurai product was apparently independent of the initial monosilyl acetal reactant configuration.

AB - Alkyl esters were reduced with iBu2AlH or a 1:1 mixture of iBu2AlH and iBu3Al (iBu2AlH·iBu3Al or iBu5Al2H), followed by trapping of the resulting tetrahedral intermediate with TMS-imidazole to produce monosilyl acetals. Reaction of the mixed acetals with allyltrimethylsilane in the presence of Lewis acids (Hosomi-Sakurai reaction) generated homoallylic alcohols or ethers selectively, depending on the substitution of the monosilyl acetal. TMS methoxy acetals (MeO-CH-OTMS) and TMS ethoxy acetals bearing additional complexing groups such as MeO- or Ph2C=N- provided alcohols with 1.5:1-9:1 threoselectivity, while simple TMS ethoxy acetals provided only ethyl ethers as products. The monosilyl acetal configuration was easily epimerized or racemized, and the configuration of the Hosomi-Sakurai product was apparently independent of the initial monosilyl acetal reactant configuration.

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