Ketene diethyl acetal

Following a similar strategy, trifluoro acetyl ketene diethyl acetal was successively condensed with 2-aminothiophenol in the presence of toluene in a multimode microwave oven (8 min at 980 W) to give the 2-(l,l,l-trifluoro-acetonyl)benzothiazole ring in an excellent yield (93%) [14] (Scheme 13). hi this work, the temperature reached during reaction was not controlled reducing the reproducibility of the process. 

Table I records the results obtained in the preparation of 30 cycloaddition products from the acridizinium cation. As was demonstrated by Fields, Regan, and Dignan, even preparative experiments done at different temperatures and in different solvents are adequate to prove the inverse electron demand character of the reaction. Nucleophilic alkenes, like ketene diethyl acetal, reacted in minutes at room temperature while the strongly electrophilic alkene, tetracyanoethylene, failed to react under any conditions.

Truce and Norrell noticed in 1963 that sulfenes readily undergo 2 - - 2 cycloaddition to ketene diethyl acetal with the formation of 3,3-diethoxythie-tane 1,1-dioxides. The same reaction was carried out by Paquette, using 1,1-dioxide ketals with cyclic a-halo sulfones in which the corresponding chloroketal derivatives 47 were formed. This approach may be illustrated by the addition of ketene diethyl acetal to halogenated sulfenes and to... 

Schroeter, S.H. and Orlando, C.M. Jr (1969) Photocydoaddition of various ketones and aldehydes to vinyl ethers and ketene diethyl acetal. Journal of Organic Chemistry, 34 (5), 1181-1187. 

ANTHRAQUINONES Alkyllithium reagents. Cirignard reagents. Ketene diethyl acetal. 

The cycloaddition of ketene diethyl acetal to benzo[6]quinolizinium salt 247, followed by hydrolysis and thermolysis, gave over-crowded 1-pyridyl-8-rerf-butylnaphthalene 248. The naphthalene 248 was oxidized electro-chemically or with anhydrous CuCl2 to afford azoniafluoranthene salt 249,... 

CYCLOADDITION Alumina chloride. l,2-Bis(trimethylsilyloxy)cyclo-butene. 2,2-Dimethyl-3(2/T)-furanone. Ethylaluminum dichloride. Ketene diethyl acetaL Methyl cyclobutene-carboxylate. Trimethyl-1,3-diox olen-one. Zinc chloride. 

Coumarin has been studied extensively in this context in the absence of a sensitiser, it gives a syn head-to-head dimer in the presence of benzophenone as sensitiser, the anti isomer is formed the syn head-to-tail dimer is obtained by irradiation in acetic acid. Cyclobutane-containing products are obtained in modest yields by sensitiser-promoted cycloadditions of coumarins or 3-acyl-oxycoumarins, with alkenes, ketene diethyl acetal or cyclopentene. ... 

Reaction of methanedisulfonyl chloride (103) with enamines in the presence of triethylamine gave an acyclic product 104 (equation 78)76. The formation of 104 is to be contrasted with the double four-membered ring cycloadduct obtained in the reaction of 103 with ketene diethyl acetal (see Section V.B.2). 

Ketene diethyl acetals, which are more nucleophilic than vinyl ethers, add to a wide array of sulfenes to produce [2 + 2] cycloadducts36 39,207. The reaction of meth-anesulfonyl chloride with ketene diethyl acetal gave 3,3-diethoxythietane 1,1-dioxide, which can be hydrolyzed to 3-oxothietane 1,1-dioxide by concentrated hydrochloric acid (equation 97)207. The reaction of methanesulfonyl chloride with two equivalents of ketene... 

Shipov and coworkers80 recently reported that (trimethylsilyl)methanesulfonyl chloride in the presence of triethylamine reacts with ketene diethyl acetal to produce a [2 + 2] cycloadduct in 95% yield (equation 100). 

Benzoylketene diethyl acetal207 has been found to undergo [4 + 2] cycloaddition with phenylsulfene to give a (5-sultone (116) (equation 101), whereas acetyl ketene diethyl acetal gave 118, perhaps via 117 (equation 102)207. 

Reaction of 1,3-propanedisulfonyl chloride (100) with two equivalents of ketene diethyl acetal gave the double cycloadduct 119 (equation 104) like the corresponding enamine... 

As has been noted already in Section IV.A.2, Tokura and coworkers92 used benzenesul-fonyl fluoride and phenyllithium to generate phenylsulfene, which reacted with ketene diethyl acetal to give a [2 + 2] cycloadduct (equation 107). 

The structure and stereochemistry of the products of acetone-sensitized photoaddition of 1,3-dimethyluracil to keten diethyl acetal, t-butyl vinyl ether, and vinyl acetate have been elucidated 129 cis- and trans-fustd 8,8-diethoxy-2,4-diazabicyclo[4,2,0]octane-3,5-diones (157) and (158) are obtained in the ratio... 

Readily available methylthiomaleic anhydride reacts smoothly with dienes giving Diels-Alder adducts [e.g. (149) from 2-methyl-buta-1,3-diene] which are transformed to j8-keto-ester ketals, e.g. (150), by oxidative decarboxylation (cf. ref. 49). Intermediate (149) can also be converted into the corresponding a-methylene-ketone or oxidized to salicylic esters. a-Nitroacetoacetates (151) have been prepared by condensing a-nitroacetates with ketene diethyl acetal followed by hydrolysis of the acetoacetate enol ether thus formed. 

The in situ creation of methylchloroketene from n-chloropropionyl chloride and triethylamine in the presence of ketene diethyl acetal led to... 

Yamomoto reported an interesting carbocyclic inverse electron demand Diels-Alder reaction between tropone (25) and ketene diethyl acetal (26) catalyzed by tris(pentafluoro)phenylborane. Under these conditions, Diels-Alder product 27 is formed almost exclusively, while most other catalysts (including BF3 and BPhs) favor sole production of the [8 + 2] cycloadduct 28. Yamamoto also described the development of an asymmetric version of this Diels-Alder reaction. ... 

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