Related Experiment Video
Updated: Jun 3, 2025
07:50
Efficient Synthesis of All-Carbon Quaternary Centers via the Conjugate Addition of Functionalized Monoorganozinc Bromides
Published on: May 26, 2019
9.2K
TBAT-Catalyzed Dioxasilinane Formation from Beta-Hydroxy Ketones.
1Department of Chemistry, Western Washington University, Bellingham, WA 98225 (USA).
Tetrahedron
|January 13, 2025
Summary
Ruthenium catalysts enable beta-hydroxy ketone reduction via silyl etherification and hydrosilylation. Using tetrabutylammonium difluorotriphenylsilicate (TBAT) yields cyclic dioxasilinanes, which can be converted to protected 1,3-diols.
Area of Science:
- Organic Chemistry
- Catalysis
- Synthetic Methodology
Background:
- Beta-hydroxy ketones are versatile synthetic intermediates.
- Efficient reduction and functionalization methods are crucial for complex molecule synthesis.
Purpose of the Study:
- To develop a novel synthetic route for the reduction and functionalization of beta-hydroxy ketones.
- To explore the utility of tetrabutylammonium difluorotriphenylsilicate (TBAT) in ketone transformations.
Main Methods:
- Ruthenium-catalyzed silyl etherification followed by intramolecular hydrosilylation.
- Direct conversion using tetrabutylammonium difluorotriphenylsilicate (TBAT).
- Column chromatography for purification and regioselective ring-opening with organolithium reagents.
Main Results:
- A two-step sequence using ruthenium catalysis and tetrabutylammonium fluoride (TBAF) effectively reduced beta-hydroxy ketones.
- Switching to TBAT allowed direct formation of cyclic dioxasilinanes from beta-hydroxy ketones.
- Dioxasilinanes were regioselectively opened to yield differentiated 1,3-diols with selective secondary alcohol protection.
Conclusions:
- TBAT promotes a novel transformation of beta-hydroxy ketones to cyclic dioxasilinanes.
- This method provides access to selectively protected 1,3-diols.
- A proposed mechanism involving TBAT-catalyzed silyl ether formation and intramolecular carbonyl hydrosilylation is supported by diastereoselectivity data.
Related Concept Videos
02:44Oxidation of Alkenes: Syn Dihydroxylation with Osmium Tetraoxide
9.8K
Alkenes are converted to 1,2-diols or glycols through a process called dihydroxylation. It involves the addition of two hydroxyl groups across the double bond with two different stereochemical approaches, namely anti and syn. Dihydroxylation using osmium tetroxide progresses with syn stereochemistry.
9.8K
02:04Oxidation of Alkenes: Anti Dihydroxylation with Peroxy Acids
5.6K
Diols are compounds with two hydroxyl groups. In addition to syn dihydroxylation, diols can also be synthesized through the process of anti dihydroxylation. The process involves treating an alkene with a peroxycarboxylic acid to form an epoxide. Epoxides are highly strained three-membered rings with oxygen and two carbons occupying the corners of an equilateral triangle. This step is followed by ring-opening of the epoxide in the presence of an aqueous acid to give a trans diol.
5.6K
03:08Hydroboration-Oxidation of Alkenes
7.8K
In addition to the oxymercuration–demercuration method, which converts the alkenes to alcohols with Markovnikov orientation, a complementary hydroboration-oxidation method yields the anti-Markovnikov product. The hydroboration reaction, discovered in 1959 by H.C. Brown, involves the addition of a B–H bond of borane to an alkene giving an organoborane intermediate. The oxidation of this intermediate with basic hydrogen peroxide forms an alcohol.
7.8K
01:57Preparation of Diols and Pinacol Rearrangement
3.3K
Compounds bearing two hydroxyl groups are known as diols. When the hydroxyl groups are located on adjacent carbon atoms, the diols are called vicinal diols or glycols. Under acidic conditions, vicinal diols undergo a specific reaction called pinacol rearrangement.
The reaction begins with transferring a proton from the acid catalyst to one of the hydroxyl groups, producing an oxonium ion.
The reaction begins with transferring a proton from the acid catalyst to one of the hydroxyl groups, producing an oxonium ion.
3.3K
02:47Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
17.8K
Introduction
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
17.8K
03:00Preparation of Epoxides
7.4K
Overview
Epoxides result from alkene oxidation, which can be achieved by a) air, b) peroxy acids, c) hypochlorous acids, and d) halohydrin cyclization.
Epoxidation with Peroxy Acids
Epoxidation of alkenes via oxidation with peroxy acids involves the conversion of a carbon–carbon double bond to an epoxide using the oxidizing agent meta-chloroperoxybenzoic acid, commonly known as MCPBA. Since the O–O bond of peroxy acids is very weak, the addition of electrophilic oxygen of...
Epoxides result from alkene oxidation, which can be achieved by a) air, b) peroxy acids, c) hypochlorous acids, and d) halohydrin cyclization.
Epoxidation with Peroxy Acids
Epoxidation of alkenes via oxidation with peroxy acids involves the conversion of a carbon–carbon double bond to an epoxide using the oxidizing agent meta-chloroperoxybenzoic acid, commonly known as MCPBA. Since the O–O bond of peroxy acids is very weak, the addition of electrophilic oxygen of...
7.4K