Heteroacylsilanes: synthesis and synthetic potentialities of new nucleophilic acylation agents

Ricci, Alfredo; Degl’Innocenti, Alessandro; Chimichi, Stefano; Fiorenza, Mariella; Rossini, Gabriele

doi:10.1021/jo00201a029

Cited by 60 publications

(15 citation statements)

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“…Using thiol ester 1a as the model substrate, various silyl metal reagents 4,8 were tested for ketone synthesis using [PdCl 2 (PPh 3 ) 2 ]. However, silylating reagents, which act as silyl anion sources, did not provide the desired acylsilane (Scheme 3).…”

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confidence: 99%

Synthesis of Acylsilanes by Palladium-catalyzed Cross-coupling Reaction of Thiol Esters and Silylzinc Chlorides

Azuma¹,

Okano²,

Tokuyama³

2011

Chem. Lett.

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An acylsilane synthesis by a Pd-catalyzed cross-coupling reaction of thiol esters and silylzinc chlorides was developed. S-Phenyl thiol esters with a variety of functional groups were converted to corresponding acylsilanes.Since acylsilanes possess a variety of unique reactivities, 1 their synthesis has been an important research topic in organic chemistry.1p1r,24 Brook 2a and Corey 2b independently reported representative methods to prepare acylsilanes by silylation of a lithiated dithiane followed by removal of dithiane. Acylsilanes are also synthesized by 1,2-addition of silyllithium to aldehydes followed by oxidation according to a procedure of Reich. 5However, both methods have only limited functional group compatibility since they use strong bases such as n-BuLi. To circumvent these problems, palladium-catalyzed cross-coupling of acid chlorides with disilane 4a4d or stannylsilane 4e has recently been reported. These methods, however, are unsatisfactory because they require harsh conditions such as heating at high temperature without solvent. On the other hand, thiol esters are a suitable substrate for cross-coupling reactions based on oxidative addition of a transition-metal catalyst to the CS bond. 6,7 Under this background, we initiated a study of the transformation of thiol esters to acylsilanes. Herein, we report a mild synthesis of acylsilanes by palladium-catalyzed crosscoupling of thiol esters and silylzinc chlorides.Based on the proposed reaction mechanism for the palladium-catalyzed cross-coupling reaction of thiol esters with organozinc reagent (Scheme 1), we considered a working hypothesis for transformation of thiol esters to acylsilanes as shown in Scheme 2. Oxidative addition of palladium(0) to the CS bond of the thiol ester gives acyl palladium species which should be transformed to the acylsilane via transmetalation with a silyl metal reagent followed by reductive elimination with regeneration of Pd(0).With this idea in mind, we explored a suitable silyl metal reagent for the expected cross-coupling reaction. Using thiol ester 1a as the model substrate, various silyl metal reagents 4,8

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confidence: 99%

Synthesis of Acylsilanes by Palladium-catalyzed Cross-coupling Reaction of Thiol Esters and Silylzinc Chlorides

Azuma¹,

Okano²,

Tokuyama³

2011

Chem. Lett.

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“…The reactivity of enynyl azide 1p bearing a tert -butyldimethyl silyl (TBS) group on the alkyne was also tested and found that under both reaction conditions, AuCl 3 (10 mol %)/AgSbF 6 (30 mol %) in CH 3 CN at 80 °C (entry 2a) and I 2 /NaHCO 3 in CH 2 Cl 2 at room temperature (entry 2b), 2-silylketopyrrole 2p was obtained in 34% and 48% yield, respectively. Acyl silanes are versatile intermediates and, to the best of our knowledge, their synthesis is less explored, mainly heteroacyl silanes . Noteworthy the enynyl azide 1q , prepared from a non-MBH-product, was successful in providing the corresponding 2-ketopyrrole 2q in the presence of AuCl 3 (10 mol %)/AgSbF 6 (30 mol %) in CH 3 CN at 80 °C, albeit in low yield (38%, entry 3a).…”

Section: Resultsmentioning

confidence: 99%

Oxidative Aza-Annulation of Enynyl Azides to 2-Keto/Formyl-1H-pyrroles

2017

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A method for the construction of pyrroles bearing a 2-keto or formyl group through the intramolecular oxidative aza-annulation of enynyl azides is reported for the first time. It involves a sequential carbon-nitrogen/carbon-oxygen bond formations, and the combination of AuCl with AgSbF was identified as a suitable reagent system to promote the present reaction. The required enynyl azides are readily prepared from Morita-Baylis-Hillman (MBH) acetates of acetylenic aldehydes.

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“…Phenyl isocyanate, cyclohexanecarbonyl chloride ( 11j ), benzoyl chloride ( 11a ), 4‐ tert ‐butylbenzoyl chloride ( 11b ), thiophene‐2‐carbonyl chloride ( 11f ), furan‐2‐carbonyl chloride ( 11l ), acetyl chloride ( 11i ), acetic anhydride, and norborna‐2,5‐diene were purchased from Aldrich, 4‐ n ‐heptyloxybenzoyl chloride ( 11d ) from Lancaster, and were used as received. 1,4‐Bis(2 H ‐tetrazol‐5‐yl)benzene ( 4 ) (BTB),23 5‐cyanotetrazole ( 7 ),26 cyclooctyne,27 1‐methoxycyclopentene,28 4‐octylbenzoyl chloride ( 11c ),29 5‐ethyl‐ and 5‐octylthiophene‐2‐carbonyl chlorides ( 11k ) and ( 11g ),30 and N ‐methylpyrrole‐2‐carbonyl chloride ( 11m )31 were prepared according to literature procedures. 4‐Octadecylbenzoyl chloride was prepared from 4‐octadecylbenzoic acid32 by treatment with thionyl chloride.…”

Section: Methodsmentioning

confidence: 99%

3,6-Bis(2H-tetrazol-5-yl)-1,2,4,5-tetrazine: A Versatile Bifunctional Building Block for the Synthesis of Linear Oligoheterocycles

et al. 2001

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Heteroacylsilanes: synthesis and synthetic potentialities of new nucleophilic acylation agents

Cited by 60 publications

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Synthesis of Acylsilanes by Palladium-catalyzed Cross-coupling Reaction of Thiol Esters and Silylzinc Chlorides

Synthesis of Acylsilanes by Palladium-catalyzed Cross-coupling Reaction of Thiol Esters and Silylzinc Chlorides

Oxidative Aza-Annulation of Enynyl Azides to 2-Keto/Formyl-1H-pyrroles

3,6-Bis(2H-tetrazol-5-yl)-1,2,4,5-tetrazine: A Versatile Bifunctional Building Block for the Synthesis of Linear Oligoheterocycles

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