A Remarkable Solvent Effect on the Reductive Silylation of Carboxylic Esters. Preparation of 1,1-Bis(trimethylsilyl)-1-alkanols

Kuwajima, Isao; Minami, Naoki; Abe, Toru; Sato, Toshio

doi:10.1246/bcsj.51.2391

Cited by 21 publications

(3 citation statements)

References 4 publications

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“…The alcohols were prepared in reasonable yields by hydrolysis of the bis(trimethylsilyl) carbinol silyl ethers 94,95 , which in turn were produced from the corresponding esters using another silyl acyloin reaction, which itself, ironically, proceeds through an acyl silane intermediate (Scheme 21) 94 .…”

Section: Preparation From Enol Ethersmentioning

confidence: 99%

Acyl Silanes

Page¹,

McKenzie²,

Klair³

et al. 2009

Patai's Chemistry of Functional Groups

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Section: Preparation From Enol Ethersmentioning

confidence: 99%

Acyl Silanes

Page¹,

McKenzie²,

Klair³

et al. 2009

Patai's Chemistry of Functional Groups

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“…Extending this observation, we recalled that Kuwajima et al had recommended lithium alkoxides derived from 1,1-bis(trimethylsilyl) alcohols as hindered bases in controlled aldol reactions [21] [24]. We imitated one of these, the reaction between methyl isopropyl ketone 16 and pentanal 15, using the lithium alkoxide 17 derived from pivaloyl chloride (Scheme 4).…”

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confidence: 94%

“…± The Preparation of 1,1-Disilyl Alcohols. 1,1-Bis(trimethylsilyl) alcohols such as the alcohol 11 have been prepared by Kuwajima et al by reductive silylation of esters with Na and Me 3 SiCl in refluxing THF, followed by acidic hydrolysis to remove the O-silyl group [21]. We repeated this synthesis with small a modification.…”

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confidence: 99%

1,1-Disilyl Alcohols as d1 Synthons: Harnessing the 1,2-Brook Rearrangement

Fleming¹,

Lawrence²,

Surry³

et al. 2002

HCA

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Dedicated to Professor Dieter Seebach on the occasion of his 65th birthday 1,1-Disilyl alcohols like 6 give the silyl ethers like 9 on treatment with base and alkyl halides, in a reaction which may be formulated as the alkylation of the Brook-rearranged carbanion 8. The products can be oxidised to give ketones like 10, showing that this Brook-rearranging system supplies a controlled d 1 synthon of the acyl anion class. The alcohols can be prepared from the acid chloride 12 and dimethyl(phenyl)silyllithium, but the intermediate anion 21 need not be worked up; it can be used directly in the alkylation step.Introduction. ± The 1,2-Brook rearrangement is usually formulated as an equilibrium between an oxy anion having an a-silyl substituent, such as 1, and a carbanion having an a-silyloxy substituent, such as 2, with the former normally in high concentration and the latter in low concentration [1]. Whether or not this is an accurate description of the species present 3 ), it often reacts with electrophiles as a carbon nucleophile, and as such it can be classified as a d 1 synthon [3].For example, if benzaldehyde (PhCHO) is treated with dimethyl(phenyl)silyllithium (Me 2 PhSiLi) the products are the a-silylbenzyl alcohol 3 and, after workup, the pinacol 4 (Scheme 1) [4]. The latter is the product from the reaction of an anion 2 with another molecule of PhCHO, but it is not possible to use this nucleophile with a range of electrophiles. Although homocoupling is relatively easy, as here, it is limited to aromatic aldehydes and ketones [5], because easy Brook rearrangement 1 3 2 needs the stabilisation of the carbanion provided by the aromatic ring. We have found, as Kuwajima and co-workers have also [6], that it can also be made to give a cross-coupled pinacol 5, but only when the electrophilic component is a nonenolisable aldehyde [7]. The yield was low, there were several other products, and it was clear that this was not a general or reliable way of gaining access to a reliable d 1 synthon.The Brook rearrangement can be set up in several ways: most commonly when an a-silylcarbinol is treated with base [8], when an aldehyde or ketone is treated with a silyllithium reagent [9], or when an acylsilane is treated with a nucleophile [10]. There are a few reactions in which a Brook rearrangement, set up in one of these ways, is the

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