Wolff rearrangement of (1-diazo-2-oxoalkyl) silanes

Brückmann, Ralf; Schneider, Klaus; Maas, Gerhard

doi:10.1016/s0040-4020(01)89498-9

Cited by 40 publications

(20 citation statements)

References 32 publications

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“…Synthesis of highly substituted arenes from diazo ketones and 1-methoxybutyne (317 Ǟ 322) [ [261] CO 2 R, and PO(OR) 2 . [262] It should be noted that α-silyl-α-diazo ketones, RЈCOϪCN 2 SiR 3 , undergo Wolff rearrangement on photolysis [263] and rhodium(II) catalysis [264] whereas thermolysis proceeds by way of a silyl shift from carbon to oxygen. [265] Photolysis of 317, R 1 ϭ SiR 3 , in the presence of electron-poor alkenes, [261a] imines, and keto esters [261b] afforded cyclohexenones 330, unsaturated lactams 331, and lactones 332, respectively (Scheme 44).…”

Section: Scheme 41 [2ϩ2] Cycloaddition Reactions Of Ketenes With Iminesmentioning

confidence: 99%

100 Years of the Wolff Rearrangement

2002

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The conversion of α‐diazo ketones into ketenes, and products derived therefrom, was discovered by Wolff in 1902. Major applications of the Wolff rearrangement, such as the Arndt−Eistert reaction (homologation of carboxylic acids) and the ring contraction of cyclic ketones, have been with us for some while. Nevertheless, substantial progress has been made recently. The reaction mechanism has been explored by means of matrix isolation, time‐resolved spectroscopy, and computation. Full retention of configuration of the migrating group has been established by using enantioselective chromatography. The Arndt−Eistert reaction has witnessed a renaissance in the field of natural products, in particular β‐amino acids and β‐peptides. Ring‐contracting Wolff rearrangements and ketene cycloadditions have been applied in syntheses of increasingly complex, biologically active target molecules. These accomplishments, as well as unsolved problems, are addressed in the present review. (© Wiley‐VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

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Section: Scheme 41 [2ϩ2] Cycloaddition Reactions Of Ketenes With Iminesmentioning

confidence: 99%

100 Years of the Wolff Rearrangement

2002

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“…Usually, silyl ketenes are prepared from silyldiazo ketones such as 2 in an additional step by a photochemical [10,14,15] or transition-metal (copper [14] or rhodium [4] ) catalyzed Wolff rearrangement. Attempts to isolate silyldiazo ketone 2c met with another surprise (Scheme 4): diazo ketone 1b was trimethylsilylated in ether in the presence of NEtiPr 2 as usual, the precipitated ammonium salt was filtered off, and the solvent was removed completely.…”

Section: Resultsmentioning

confidence: 99%

“…[4b, 8,14] and 3d [4b] have been synthesized before by photochemical or rhodium-catalyzed decomposition of the corresponding silyldiazo ketone. …”

Section: Ketenes 3bmentioning

confidence: 99%

Aryl Trialkylsilyl Ketenes: Acid‐Catalyzed Synthesis from 1‐Aryl‐2‐diazo‐2‐trialkylsilylethanones and Their Conversion into 3‐Silyl‐1‐silyloxyallenes

2008

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Aryl‐substituted α‐silyl α‐diazo ketones are readily transformed into aryl silyl ketenes in the presence of a catalytic amount of triflic acid. Thus, a convenient method to prepare these silyl ketenes becomes available, which combines two steps, silylation of an aryl diazomethyl ketone and acid‐induced Wolff rearrangement of the formed α‐silyl α‐diazo ketone, in a one‐pot procedure. It appears that the trialkylammonium salt, which is formed in the silylation step, can also catalyze the Wolff rearrangement, but distinctly more slowly than the proton acid. The silyl ketenes react smoothly with α‐silyl α‐diazo ketones to form 3‐silyl‐1‐silyloxyallenes in fairly good yields. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

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“…(1-Diazo-2-oxoalkyl)silanes 1a, [31] 1b, [32] and 1c [31] were prepared as published. Yields higher than those reported were -syn-cis-Isomer 5aA), and 4-[(Z)-2,2-Dimethyl-1-(triisopropylsilyloxy)propylidene]-2,3a-diphenyl-3a,4-dihydrophosphireno[1,2-b][1,2]thiaphosphole (6a): A solution of thiaphosphole 3a (0.424 g, 1.67 mmol) and diazo ketone 1a (0.471 g, 1.67 mmol) in dichloromethane (15 mL) was stirred at 20°C for 15 h. The solvent was evaporated and the residue was subjected to column chromatography (silica gel, diethyl ether/petroleum ether, 1:14).…”

Section: Methodsmentioning

confidence: 99%

Cycloaddition Behavior of 1,2‐Thiaphospholes: Reactions with Diazocumulenes and with Cyclopentadiene

2003

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1,2-Thiaphospholes 3a,b react with (1-diazo-2-oxoalkyl)silanes 1a−c to form [1,2] ,2]thiaphosphole systems 4 with cis-anti-cis configuration of the tricyclic framework. They are accompanied by small amounts of compounds 5 that are presumably the cis-syn-cis isomers of 4, and 6-alkylidene-1-phospha-2-thiabicyclo[3.1.0]hex-3-enes 6. It is likely that these reactions proceed by [3+2] cycloaddition of diazocumulenes, which coexist with diazo compounds as minor equilibrium components, at the P=C bond of the heterophospholes, followed by N 2 elimination and formation of short-lived 2-alkylidene-

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Wolff rearrangement of (1-diazo-2-oxoalkyl) silanes

Cited by 40 publications

References 32 publications

100 Years of the Wolff Rearrangement

100 Years of the Wolff Rearrangement

Aryl Trialkylsilyl Ketenes: Acid‐Catalyzed Synthesis from 1‐Aryl‐2‐diazo‐2‐trialkylsilylethanones and Their Conversion into 3‐Silyl‐1‐silyloxyallenes

Cycloaddition Behavior of 1,2‐Thiaphospholes: Reactions with Diazocumulenes and with Cyclopentadiene

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