Feist

Feiste, K.L. Stegemann, D. Reimehe, W. Three dimensional analysis of growing casting defects. International Symposium on Computerized Tomography for Industrial Applieatlons, 8.10. Junl 1994, Berlin... 

Hantzsch and Feist Syntheses. The Hant2sch synthesis of pyrroles iavolves condensation of an a-haloketone (10) with a p-keto ester (6) ia the presence of ammonia or an amine (22). 

The Feist synthesis is similar to the Hant2sch method and iavolves condensation of acyloias, eg (11), with aminocrotonic esters, eg (12), ia the presence of 2iac chloride (23). 

FEIST - SENARY Furan Synthesis Synthesis ol lurans by condensation ol an a-halocarbonyl compound with an enol. 

Palmatine and Associated Alkaloids. Palmatine, jatrorrhizine (jateorhizine) and columbamine were first isolated from ealumba root (Jateorhiza palmata Lam., Miers) as a result of the work of Giinzel followed by that of Feist, but all three have sinee been found in other genera. All three are quaternary bases, soluble in water, and methods for their isolation have been deseribed by Giinzel, Feist, and Spath and Polgar, usually dependent upon their preeipitation as iodides, or their reduetion to the tertiary tetrahydro-bases. The latter oeeur naturally in the Rhceadales and have been deseribed already (p. 284). A method for the separate estimation of the alkaloids of ealumba root has been described by Neugebauer and Brunner. " ... 

Zupan, M. Co//ec Czech Chem. Commun 1977,42,266 Zupan, M Poliak, A 7. Chem. Soc, Chem. Commun 1975, 715 Sket, B, Zupan, M. Zupet, P. Tetrahedron 1984,40, 1603 Naumann, D. Feist, H. R. 7 Fluorine Chem 1980, 75, 541 Naumann, D Schmeisser, M, Deneken, L Inorg Nucl Chem, Herbert H Hyman Memorial Volume, 1976, 13... 

The Feist-Benary furan synthesis occurs when an a-halocarbonyl (1) reacts with a P-dicarbonyl (2) in the presence of a base. The resulting product (3) is a 3-furoate that incorporates substituents present in the two starting materials. ... 

In 1902 Feist first described the combination of chloroacetone (4) and diethyl 3-oxoglutarate (5) in the presence of ammonia to yield trisubstituted furan 6 ... 

In 1911 Benary reported a modification of Feist s original procedure. He reacted chloroacetaldehyde (8), generated in situ from the ammonia promoted decomposition of 1,2-dichloroethyl ethyl ether (7), with ethyl acetoacetate (9) and ammonia to yield ethyl 2-methyl 3-furoate (10). ... 

The mechanism of the Feist-Benary reaction involves an aldol reaction followed by an intramolecular 0-alkylation and dehydration to yield the furan product. In the example below, ethyl acetoacetate (9) is deprotonated by the base (B) to yield anion 10 this carbanion reacts with chloroacetaldehyde (8) to furnish aldol adduct 11. Protonation of the alkoxide anion followed by deprotonation of the [i-dicarbonyl in 12 leads to... 

Syntheses of trisubstituted furans are much less common than the disubstituted derivatives only one 2,4-disubstituted 3-furoate has been prepared using the Feist-Benary reaction. Combination of chloroacetone (4) with ethyl acetoacetate (9) provides ethyl 2,4-dimethyl-3-furoate (28) in 54-57% yield. The procedure for this... 

The only tetrasubstituted furans that have been prepared using the Feist-Benary reaction are substituted tetrahydrobenzofurans and octahydrodibenzofurans. This strategy was pioneered by Stetter and Chatterjea and applied in a series of total syntheses by Magnus. Stetter demonstrated that 1,3-cyclohexanedione (30) can act as the P-dicarbonyl component and readily combines with either 3-bromo-2-ketobutyric (29) acid or ethyl 2-chloroacetoacetate (32) in the presence of potassium hydroxide to yield tetrahydrobenzofuran derivatives 31 and 33, respectively. ... 

Chatteijea showed that cyclic ot-halocarbonyls are acceptable substrates for the Feist-Benary furan synthesis by combining 1-chlorocyclohexanone (34) with 1,3-cyclohexanedione (30) to yield octahydrodibenzofuran 35. ... 

Magnus prepared tetrahydrobenzofuran 37 using a Feist-Benary reaction of ethyl 2-chloroacetoacetate (32) and functionalized 1,3-cyclohexanedione 36. Compound 37 was a key synthetic intermediate in Magnus s synthesis of linderalactone, isolinderalactone, and niolinderalactone. ... 

Several modifications of the Feist-Benary furan synthesis have been reported and fall into two general classes 1) reactions that yield furan products 2) reactions that yield dihydrofuran products. One variant that furnishes dihydrofiirans uses substrates identical to the traditional Feist-Benary furan synthesis with a slight modification of the reaction conditions. The other transformations covered in this section involve the combination of P-dicarbonyls with reagents that are not simple a-halocarbonyls. Several reactions incorporate a-halocarbonyl derivatives while others rely on completely different compounds. 

Several variations of the Feist-Benary reaction furnish substituted furans as products. The following three examples provide synthetically useful alternatives to the standard reaction conditions. One method is based on the reaction of a sulfonium salt with a P-dicarbonyl compound. For example, reaction of acetylacetone (39) with sulfonium salt 38 in the presence of sodium ethoxide yields 81% of trisubstituted furan 40. This strategy provides a flexible method for the preparation of 2,3,4-trisubstituted furans. 

Step reaction provides an excellent alternative to the traditional Feist-Benary protocol for the synthesis of 2-substituted 3-furoates. 

Three other modifications of the standard conditions provide synthetically useful strategies for the preparation of dihydrofurans. One method, called the interrupted Feist-Benary reaction, utilizes milder reaction conditions to stop the final dehydration step. For example, Calter combined bromide 47 with dicarbonyl 48 to produce dihydrofuran 49 as a mixture of diastereomers. He examined the scope and diastereoselectivity of this process and applied this reaction toward the synthesis of the polycyclic core of the zaragozic acids. A method principally designed to yield practical syntheses of cyclic ketodiesters also furnished a dihydrofuran via a variation of the interrupted Feist-Benary reaction. ... 

The final variation of the Feist-Benary furan synthesis encompasses reactions of 1,3-dicarbonyls with 1,2-dibromoethyl acetate (52). For example, treatment of ethyl acetoacetate (9) with sodium hydride followed by addition of 52 at 50°C yields dihydrofuran 53. The product can be easily converted into the corresponding 2-methyl-3-furoate upon acid catalyzed elimination of the acetate, thus providing another strategy for the synthesis of 2,3-disubstituted furans. 

For variations of the Feist-B6nary reaction that yield mixtures of furans or furan byproducts, see (a) Lavoisier-Gallo, T. Rodriguez, J. Synth. Commun. 1998, 28, 2259. (b) Courtheyn, D. Verhe, R. De Kimpe, N. De Buyck, L. Schamp, N. J. Org. Chem. 1981, 46, 3226. 

Although it is far more common to synthesize these substrates using the Feist-Benary reaction (Section 4.1), the Paal-Knorr reaction can also be used to prepare 2,3-disubstituted furans. In a recent example, Castagnoli converted 1,4-ketoaldehyde 40 into furan 41 in 97% yield upon exposure to hot sulfuric acid. ... 

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