Spiro furan-2

Examples of neighboring group participation in isoxazole bromination have been reported. When the isoxazolylpropanol (80) was treated with bromine in pyridine, it gave the spiro (furan-2,5-isoxazole) (81) (74BAU2566). The corresponding propenoic acid gave 82 [76JCS(P1)1694], whereas a similar process accounts for the reaction of... 

Spiro[furan-2(5//),l (2 //)-naphthalene] rather than a 1, 2,2, 5-tetrahydro derivative or spiro[naphthalene-l(2tf),2 -oxacyclopent[3]ene] rather than a 1,2-dihydro derivative... 

Fluorimetric methods for the determination of amino acids are generally more sensitive than colorimetric methods. Fluorescamine (4-phenyl-spiro[furan-2(3H),l -phthalan]-3,3 -dione) and o-phthaldialdehyde (OPA) substances are used for protein analysis. Fluorescamine reacts with amino groups to form fluorophores that excite at 390 nm and emit at 475 nm (Weigele et al., 1972). Applications of fluorescamine include monitoring the hydrolysis of K-casein (Beeby, 1980 Pearce, 1979) and quantification of proteins, peptides, amino acids in extracts (Creamer et al., 1985). OPA produces fluorescence on reaction with 2-mercaptoethanol and primary amines, with strong absorption at 340 nm. Lemieux et al. (1990) claimed that this method was more accurate, convenient, and simple for estimating free amino acids than the TNBS, ninhydrin, or fluorescamine methods. 

Fluorescamine (4-phenyl-spiro[furan-2(3Fl), l -phthalan]-3,3 -dione) Fluorescent (ex. 390 nm, em. 475 nm) 20-100 pmol 30-90 min postcolumn Secondary amine pretreatment, critical concentration, may give background interference Rapid reaction, stable product, good reagent separation... 

A full account of the Ru(PyBox)-catalyzed enantioselective 13-dipolar cycloaddition between 2,3-dihydrofuran and diazopyruvates, first described in 2004, was reported <05HCA101Q>. 2,3-Dihydrofurans having a 3-acetyl group, e.g. benzocycloalla[l,2-fojfurans and spiro[furan-2(37/),r-benzocycloalkane], underwent benzannulation via photo-induced cleavage of the dihydrofuran ring <05rL7303>. An example that produced a helicene-type compound is shown below. 

Tetrabromo-r,4-dibutyl-4-(dibromomethylene)spiro[furan-2(5, 6 -[3 oxabicyclo[3.2.0 heptane]-2, 5-dione, 9CI... 

Hydroxy-1, 3,4 -tris(4-hydroxyphenyl)-3 -[2-(4-hydroxyphenyl)ethyl]-7 -(sulfooxy) spiro[furan-2(5, 2 (3 -pyrrolo[2,3-c] carbazole]-5,5 (6 -dione, H-20247 41 -Hydroxy-2,42-tritetracontapentaenediynoic acid, H-10238... 

Other Names Spiro[furan-2(5H),9 -xanthen]-5-one, 3, 6 -dihydroxy- Xanthene-9-acrylic acid, 3,6,9-trihydroxy-, y-lactone NSC 119894 Resorcinohnalein CA Index Name Spiro[furan-2(5H),9 -[9H]xanthen]-5-one, 3, 6 -dihydroxy-CAS Registry Number 1227-88-9 Merck Index Number Not listed Chemical Structure... 

Scheme 3.43 Synthesis of spiro[furan-2,4 -tetrahydroquinoline] developed by Barluenga.

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