Feist-Benary furan

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. ... 

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. ... 

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. 

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. 

Shea, K. M. Feist—Benary Furan Synthesis In Name Reactions in Heterocyclic Chemistry, Li, J. J. Corey, E. J., Eds. Wiley Sons Hoboken, NJ, 2005, 160-167. (Review). 

The method described has some features in common with the well-known, but apparently little-used, Feist-Benary furan synthesis,1 which uses an a-haloketone in place of the sulfonium salt. Acetylenic bromides suitable for preparing the sulfonium salts are readily available by well-documented procedures involving acetylenic organometallic compounds. 

The synthesis of furans from /3-ketoesters and a-halogenated aldehydes or ketones under basic conditions is known as the Feist-Benary furan synthesis (Equation 28). In most of the cases, the reaction is initiated by an aldol reaction. If the first step is alkylation, reversed regioselectivity is observed. 

P-keto ester substituted furan Feist-Benary furan synthesis... 

Z3.3. The Feist-Benary Furan Synthesis. In this synthesis, an aldol-type carbonyl-carbanion condensation and a halogen displacement by an enol are employed to bring two molecules together in a ring stmc-ture, and in this sense it resembles the Knorr synthesis. The reactants are an alpha-haloketone and a ketoester (like ethyl acetoacetate). The mechanistic details remain unclear, but a logical mechanism is shown in Scheme 4.34. This assumes the carbonyl condensation occurs first before the halogen displacement, but the reverse may be tme. 

The Feist-Benary furan synthesis, first described in 1902, is especially useful for the synthesis of substituted furan rings. This reaction occurs... 

The Feist-Benary furan synthesis is most commonly used for the preparation of 2-substituted 3-furoates, including ethyl 2-methyl-3-furoate, the original compound prepared by Benary. The resulting ester is generally converted into a carboxylic acid for use in a variety of transformations, including decarboxylation to produce the corresponding 2-substituted furan. For example, reaction of ethyl 7-methyl-3-oxooct-6-enoate with... 

Feist-Benary Furan Synthesis, Feist-Benary Condensation)... 

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