Acetylenic acetals, synthesis

The synthesis of allenes from organocopper compounds and acetylenic acetates was... 

The acetylenic acetals are easily hydrolyzed to the corresponding aldehydes in high yields in the presence of dilute acids.3-4 Acetylenic acetals have also been of value in the synthesis of ,/3-unsatu rated ethylenic acetals or aldehydes by partial catalytic hydrogenation of the triple bond.4... 

Derivation (1) Vapor-phase reaction of ethylene, acetic acid, and oxygen, with a palladium catalyst. (2) Vapor-phase reaction of acetylene, acetic acid, and oxygen, with zinc acetate catalyst. (3) From synthesis gas. 

A Cfi + C4 synthesis of citral (32) dunethyl acetal consisted of the addition of the copper-lithium compound corresponding to 20 with the acetylenic acetal 60. The reaction occurred at - 35°C in 1 hour, and yielded the pure ( )-isomer in 92% yield. Another rather long syndiesis involved addition of the lithium derivative corresponding to 20 with 3,4-dichloro-2-butanone. Three conventional steps from die product of this Grignard reaction gave geranyl acetate (25 acetate). ... 

Since 1960, the Hquid-phase oxidation of ethylene has been the process of choice for the manufacture of acetaldehyde. There is, however, stiU some commercial production by the partial oxidation of ethyl alcohol and hydration of acetylene. The economics of the various processes are strongly dependent on the prices of the feedstocks. Acetaldehyde is also formed as a coproduct in the high temperature oxidation of butane. A more recently developed rhodium catalyzed process produces acetaldehyde from synthesis gas as a coproduct with ethyl alcohol and acetic acid (83—94). 

Calcium carbide has been used in steel production to lower sulfur emissions when coke with high sulfur content is used. The principal use of carbide remains hydrolysis for acetylene (C2H2) production. Acetylene is widely used as a welding gas, and is also a versatile intermediate for the synthesis of many organic chemicals. Approximately 450,000 t of acetylene were used aimuaHy in the early 1960s for the production of such chemicals as acrylonitrile, acrylates, chlorinated solvents, chloroprene, vinyl acetate, and vinyl chloride. Since then, petroleum-derived olefins have replaced acetylene in these uses. 

Thalllum(III) Compounds. Tb allium (ITT) derivatives have been used extensively as oxidants in organic synthesis. In particular, thaUic acetate and ttifluoroacetate are extremely effective as electrophiles in oxythaHation and thaHation reactions. For example, ketones can be prepared from terminal acetylenes by means of (OOCCH ) in acetic acid (oxythaHation) (30) ... 

Vapour phase synthesis may be carried out by passing a mixture of acetylene and acetic acid through a reaction tube at 210-215°C. Typical catalysts for this reaction are cadmium acetate, zinc acetate and zinc silicate. The monomer in each of the above mentioned processes is purified by distillation. 

One of the most important routes to isoxazole and isoxazoline rings involving the formation of the 1—5 and 2—3 bonds involves the condensation of hydroxylamine with a,/8-unsaturated carbonyl compounds. This method was previously widely used, but it is now of no preparative value, though it has been recently applied to determine the configuration of oximes. " The only new modification of this synthesis is the use of the acetals (27) of a,/8-acetylenic aldehydes for preparation of 5-substituted isoxazoles (28)... 

Propiolaldehyde diethyl acetal has found numerous synthetic applications in the literature which may be briefly summarized. The compound has been utilized in the synthesis of unsaturated and polyunsaturated acetals and aldehydes by alkylation of metal-lated derivatives, " by Cadiot-Chodkiewicz coupling with halo acetylenes, " and by reaction with organocuprates. Syntheses of heterocyclic compounds including pyrazoles, isoxazoles, triazoles, and pyrimidines have employed this three-carbon building block. Propiolaldehyde diethyl acetal has also been put to use in the synthesis of such natural products as polyacetylenes " and steroids. ... 

Because of its high chemical reactivity, acetylene has found wide use in synthesis of vinyl chloride, vinyl acetate, acrylonitrile, vinyl ethers, vinyl acetylene, trichloro- and tetrachloro-ethylene etc., in oxyacetylene cutting and welding, and as a fuel for atomic absorption instruments. 

Acetylene- and Diacetylene-Expanded Cycloalkanes and Rotanes. 201 1 -42 de Meijere A, Kozhushkov SI, Khlebnikov AF (2000) Bicyclopropylidene - A Unique Tetra-substituted Alkene and a Versatile Cj-Building Block. 207 89-147 de Meijere A, Kozhushkov SI, Hadjiaraoglou LP (2000) Alkyl 2-Chloro-2-cyclopropylidene-acetates - Remarkably Versatile Building Blocks for Organic Synthesis. 207 149-227 Dennig J (2003) Gene Transfer in Eukaryotic Cells Using Activated Dendrimers. 228 227-236 de Raadt A, Fechter MH (2001) Miscellaneous. 215 327-345 Desreux JF, see Jacques V (2002) 221 123-164... 

A more complex reaction is involved in the cooligomerization of acetylenes and tert-butyl isocyanide using nickel acetate as the catalyst (Scheme 20)43 the nature of intermediate complexes leading to the formation of 2-cyano-5-terf-butylaminopyrroles has not been established. Cocyclization of tert-butyl isocyanide with coordinated hexafluoro-2-butyne gives rise to coordinated cyclopentadienone anils for molybdenum systems,44 hence the nature of acetylene substitutents and of the organometallic catalyst play crucial roles in these processes. The pyrrole products from the former reaction can be decomposed by sulfuric acid and the overall sequence provides a simple synthesis of 5-amino-2-cyanopyrroles (Scheme 20). 

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