Tetrahydrofuran tetrahydropyran

In the NTC region, back-bitiag reactioas appear to be respoasible for the formation of cycHc ethers (60,165—170). la additioa to oxetanes and tetrahydrofurans, tetrahydropyrans, oxiranes, and others are also observed (60,96,169) the tetrahydrofurans are favored. 0-Heterocycle yields of 25 to 30% have been reported for / -pentane (165,171). Conjugate and other olefins are also prominent products ia this regioa (60,169—172). 

It was reported that Pd(0)-catalyzed coupling reactions of allenic alcohols, amines and acids with hypervalent iodonium salts afforded cyclized heterocyclic tetrahydrofurans, tetrahydropyrans, pyrrolidines, piperidines, or lactones under mild conditions <99SL324>. Intramolecular 1,5-hydrogen atom transfer radical cyclization reaction of pyrrolidine derivatives was examined. Reaction of 3,4-dialiyloxy-JV-(0-bromobenzyl)pyrtolidine gave hexahydro-... 

Tetr 39 2323 (1983) (Recent Advances in the Preparation and Synthetic Applications of Oxiranes) 43 3309 (1987) (Synthetic Routes to Tetrahydrofuran, Tetrahydropyran, and Spiroketal Units of Polyether Antibiodcs and a Survey of Spiroketals of Other Natural Products) SO 8885 (1994) (Chemical and Biological Synthesis of Chiral Epoxides)... 

Tetrahydrofuran, tetrahydropyran, pyrrolidine, and piperidine skeletons can be constructed by these reactions. 

Reductive cleavage of cyclic ethers This complex is effective for reductive cleavage of cyclic ethers. The order of reactivity is epoxide > oxetane > tetrahydrofurane>tetrahydropyrane>oxepane. It is less effective for cleavage of acyclic ethers, except for methyl ethers. The reaction involves formation of a complex of the ethereal oxygen with aluminum r-butoxide followed by Sn2 displacement with lithium triethylborohydride. Steric and electronic Victors are involved, but yields are >90% in favorable cases. 

Tetrahydrofuranes, tetrahydropyranes. Use of CF3S02C1-N(C2H5)3 for synthesis of some oxygen heterocycles is formulated in equations (I)-(III). 

The oxidation of tetrahydrofuran, tetrahydropyran and dihydropyran produced y-butyrolactone and 5-valerolactone in fairly good yields. Linear ethers, conversely, produced exclusively the corresponding acids, presumably through the in situ hydrolysis of intermediate esters [116]. 

Synthesis of tetrahydrofuran, tetrahydropyran, and spiroketal units of polyether antibiotics 87T3309. 

PhjPCHjCHjPPhCHjCHjPPhCHjCHjPPhj thermogravimetric analysis tetrahydrofuran tetrahydropyran tetrahydrothiophene thin-layer chromatography N,N,N, N -tetramethylethylenediamine, (CH3),N(CHP N(CH3),... 

Constant Value of constant k j in solvent (s ) Tetrahydrofuran Tetrahydropyran... 

As cis-fused tetrahydrofuran-tetrahydropyran ring systems are found in the halichrondrins,45 the herbicidins,46 48 and octosyl acid 49 this simple one-pot preparation demonstrates unique advantages over previous approaches utilized to target these classes of compounds.50-51... 

Tetrahydrofuran Tetrahydropyran Tetramethylethylenediamine 1,1,3,3-Tetramethylguanidine 2,2,6,6-T etramethylpiperidine Trimethylsilyl... 

Butanedlol, 1,5-pentanedlol, and ethylene glycol are dehydrated to give tetrahydrofuran, tetrahydropyran and 1,4-dloxane, respectively. The filtered NAFION is treated with acetone, deionized water, and dried at 150°C to give a catalyst with original activity. 

Brocos, P. Calvo, E. Bravo, R. Pintos, M. Amigo, A. Roux, A. H. Roux-Desgranges, G. Heat capacities, excess enthalpies, and volumes of mixtures containing cyclic ethers. 3. Binary systems tetrahydrofuran, tetrahydropyran, 1,4-dioxane, or 1,3-dioxolane + cyclohexane or toluene J. Chem. Eng. Data 1999,44,67-72... 

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