Ethyl 2-propiolate

Reactivity of 2-Amino Selenazoles with Ethyl Propiolate (54) and Dimethyl Acetylene Dicarboxylate... 

In the reaction of 4-substituted 2-aminoselenazoles with ethyl propiolate and dimethylacetylene dicarboxylate. the major products obtained from such a condensation are substituted 7H-selenazolo[3,2-a]pyrimidin-7-ones (5) and not the alternative isomeric substituted 5H-selenazoles[3,2-a]pyrimidin-5-ones (6). Distinction between the alternative structures was based on infrared, ultraviolet, and NMR data (Scheme... 

In the reaction of 2-aminoselenazoIe with ethyl propiolate, in addition to compound type 7 (50% yield), compounds 8 and 9 were also isolated. Compound 7 is probably formed through the cis isomer of 8 (Scheme 55). 

Potts et al. (333) condensed dipolarophiles (DMA, dibenzoylacetylene, ethyl propiolate) with ylides (81) obtained by quaternization of 4-methyl-thiazole with an a-bromoketone or ester and subsequent deprotonation. In fact the 1 1 molar adduct obtained (82) rearranged to a pyr-rolothiazine (83). One example of this reaction is described Scheme 49. 

Ethyl propiolate reacted with (416) in boiling benzene giving ethyl l-oxo-2-phenyl-liT-pyrido[2,l-6]benzothiazole-4-carboxylate in 83% yield, and no trace of the other possible isomer was found. 

Functionalized nitroalkenes are important chenophiles in the Diels-Alder ri example, fE -methyl fi-nitroactylate is an impottant reagent in organic synthesis The nitre group can be readily eliminated the Diels-Alder reaction of fi-nitroactylate is equivalent to that of ethyl propiolate with an inverse regiochemistry fEq. 8.4. ... 

Chlordiazepoxide functions as a 1,3-dipole (a nitrone) in the reaction with ethyl propiolate to give the cycloadduct 20.247... 

It has been shown that, on treatment with base, 1-aminopy-ridinium iodide undergoes 1,3-dipolar addition with ethyl propiolate or dimethyl acetylenedicarboxylate thus the N-aminoheterocycles may serve as convenient starting materials for the synthesis of a variety of unusual fused heterocycles.8... 

The rates of hydrolysis of 3-substituted ethyl propiolates did not give a significant correlation with eq. (2). In view of the fact that the set contained only four points, this result is hardly surprising. It seems likely that if more points were available, a good correlation would have been obtained. 

E = I2, H2O, allylic bromide, ethyl propiolate, aryl iodide... 

For the Michael addition of 2,4-pentanedione enolate to ethyl propiolate, improvements in conversion were determined. This example serves also to demonstrate that proper process conditions are mandatory to have success with micro-reactor processing. A conversion of only 56% was achieved when using electroosmotically driven flow with a two-fold injection, the first for forming the enolate and the second for its addition to the triple bond (batch synthesis 89%) [151]. Using instead a stopped-flow technique to enhance mixing, a conversion of 95% was determined. 

Organic synthesis 52 [OS 52] Addition of2,4-pentanedione enolate to ethyl propiolate [8]... 

P 38] Ethanol solutions of ethyl propiolate and diisopropylethylamine were pumped via electroosmotic flow through the micro channels of the reactor [8], By mixing thereof the enolate was obtained. By subsequent contacting with the 1,3-dicarbonyl compound, the product was obtained. The temperature was set to room temperature. In a period of 20 min a volume sufficiently large for analysis was sampled. The reaction product spectra was analyzed by GC/MS via comparison with synthetic standards. The remaining amount of diketone was used for calculating conversions. 

Figure 4.70 Flow configuration for the Michael addition using 2,4-pentanedione and ethyl propiolate in a two-mixing tee microreactor [8].

The corresponding batch operation protocol refers to the following procedure [8], The 1,3-dicarbonyl compoimd (0.25-0.50 g 1.5-5.0 mmol) was added to a stirred solution of ethyl propiolate (0.15-0.49 g 1.54—5.0 mmol) and diisopropylefhylamine (0.40-1.29 g 3.00-10.00 mmol) in ethanol (50 ml). After stirring overnight, the reaction mixture was concentrated and purified by silica gel chromatography. 

OS 52[ [OS 53[ [OS 54[ [OS 55[ [R 4b[ [P 38[ In a two-micro-mixing tee chip reactor, substrates with diketone moieties of known different reactivity, such as 2,4-pentanedione, benzoylacetone and diethyl malonate, were processed, each with the same acceptor ethyl propiolate [8]. Also, a reaction with the less alkynic Michael acceptor methyl vinyl ketone was carried out. 

The effect of stoichiometry, substituent, and temperature were investigated in reactions between the hydride HCo(tdppep) (19) and a number of alkynes.175 The cr-acetylide complex (20) and the (7-alkenyl (21) are formed from the stoichiometric reaction with ethyl propiolate. However, when a ten-fold excess of ethyl propiolate is used, the acetylide complex is formed quantitatively and one equivalent of alkyne is hydrogenated to alkene. Forcing conditions and a large excess of... 

The synthesis of 2,5-dihydro-l,2-oxaphospholes via multicomponent or catalytic reactions has been published recently. For example, it was shown that the reaction of ethyl propiolate with triphenylphosphine in the presence of /V-alkylisatins leads to spiroindole-derivatives of l,2-oxaphosphpole-2-oxide (Scheme 12) [47],... 

A Baylis-Hillman type product has been obtained through a ring-opening reaction of an epoxide with an allenoate <06OL2771>. The reaction of MgL, with ethyl propiolate provides the iodo allenoate 32. This nucleophile reacts with an aryl epoxide to provide the homoallylic alcohol 33. The Z iodide is the major product formed. 

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