F-Oxetane

Azatricyclo[2.2.1.02 6]hept-7-yl perchlorate, 2368 f Azetidine, 1255 Benzvalene, 2289 Bicyclo[2.1.0]pent-2-ene, 1856 2-/ert-Butyl-3-phenyloxaziridine, 3406 3 -Chloro-1,3 -diphenyleyclopropene, 3679 l-Chloro-2,3-di(2-thienyl)cyclopropenium perchlorate, 3388 Cyanocyclopropane, 1463 f Cyclopropane, 1197 f Cyclopropyl methyl ether, 1608 2,3 5,6-Dibenzobicyclo[3.3.0]hexane, 3633 3,5 -Dibromo-7-bromomethy lene-7,7a-dihy dro-1,1 -dimethyl-1H-azirino[l,2-a]indole, 3474 2.2 -Di-tert-butyl-3.3 -bioxaziridinc, 3359 Dicyclopropyldiazomethane, 2824 l,4-Dihydrodicyclopropa[ >, g]naphthalene, 3452 iV-Dimethylethyl-3,3-dinitroazetidine, 2848 Dinitrogen pentaoxide, Strained ring heterocycles, 4748 f 1,2-Epoxybutane, 1609 f Ethyl cyclopropanecarboxylate, 2437 2,2 -(l,2-Ethylenebis)3-phenyloxaziridine, 3707 f Methylcyclopropane, 1581 f Methyl cyclopropanecarboxylate, 1917 f Oxetane, 1222... 

Oxepin-3,6-endoperoxide, see ewiio-2,3-Epoxy-7,8-dioxabicyclo[2.2.2]oct-5-ene, 2329 f Oxetane, 1218... 

Preparation of F-oxetane (1), disclosed in the patent by Kauck and Simons in 1952, was the first report on synthesis of fluorinated oxetane. It was obtained from parent hydrocarbon by electrochemical fluorination in anhydrous HF and isolated as nonflammable, water-insoluble, colorless gas with boiling point of —38°C. Much later, a direct fluorination by fluorine gas was employed to convert 2,2,3,3-tetra-fluorooxetane (2) into F-oxetane (1) or 2,2,3,3,4-pentafluorooxetane (Scheme 2.1). Varying the conditions of the fluorination, each of the two can be obtained as the major product. 

SolubiHty parameters of 19.3, 16.2, and 16.2 (f /cm ) (7.9 (cal/cm ) ) have been determined for polyoxetane, po1y(3,3-dimethyl oxetane), and poly(3,3-diethyloxetane), respectively, by measuring solution viscosities (302). Heat capacities have been determined for POX and compared to those of other polyethers and polyethylene (303,304). The thermal decomposition behavior of poly[3,3-bis(ethoxymethyl)oxetane] has been examined (305). 

Another new modification is the 2 -deoxy-2 flouro-Darabinonucleic acid (2 F-ANA), which increases the strength of the oligonucleotide-mRNA hybrids, elicits efficient RNaseH-mediated degradation of the target, is more nuclease resistant and reaches high intracellular concentrations for prolonged time. Similar results could be obtained with oxetane modified ASONs. 

Photolysis of benzaldehyde and trimethylethylene yields a mixture of cis and trans oxetanes with the two orientations shown in Eq. 42. Orientation 7 predominates and biradical intermediates generated after formation of a bond involving the lone nonbonding electron of an n, n excited benzaldehyde have been postulated. 66> Fig. 5 is the interaction diagram, the molecular parameters being based on HMO calculations, and spectroscopic experiments. 55,56,109) The orbital interaction E(n) F(n) is obviously dominant since the energy gap between F n ) and E n ) is over 4 eV. Therefore, a biradical mechanism should be postulated. The dominant orbital interaction is largest for attack of the... 

Epoxide (421a) and oxetane (421b) rings are opened by a suspension of Li in the presence of catalytic amounts of 1,4-di-f-butylbiphenyl, as shown in equation 120. The... 

D. Schmaljohan, B.I. Voit, J.F.G.A. Jansen, P. Hendrdriks, J.A. Loontjens, New Coating Systems Based on Vinyl Ether- and Oxetane-modified Hyperbranched Polyester, Macromol. Mater. Eng. 275,31-41 (2000)... 

There has been considerable variation in the choice of base used. In most cases, hot, concentrated potassium hydroxide gives good results, but sometimes potassium hydroxide in aqueous DMSO, potassium f-butoxide in DMSO or NaH in DMSO is more satisfactory (80TL585). The tercyclic oxetane (50), however, was not formed from the hydroxy-cyclic sulfate precursor under any of these conditions, but use of the amidine base (49) at room temperature produced it in 46% yield (81JOC3144). 

Mention should be made of studies of slow, controlled combustion of alkanes, where formation of oxetanes can be detected. For example, oxetane is observed during combustion of propane, while 2-f-butyl-3-methyloxetane and 2-isopropyl-3,3-dimethyloxetane are observed from combustion of isooctane. While the yields are extremely low, the presence of these compounds, along with the other products found, have provided evidence for the mechanism of combustion. The oxetanes are believed to result from rearrangement of peroxy radicals in the radical chain process (equation 114) (70MI51300,73MI51301). 

Poly (3,3-Bis(Chloromethyl)Oxetane) This is marketed by Hercules as Penton chlorinated polyether. Its thermal, flame, and chemical resistance are used primarily for corrosion-resistant equipment in the process industries, such as valves, fittings, pumps, meters, and linings for steel pipe and tanks, for service in many corrosive atmospheres up to 250°F. or higher. At 4.50/pound, growth possibilities appear limited by increasing competition from lower-cost materials. 

The ring expansion of 2-f-butyloxetanes to tetrahydrofurans in the presence of a Lewis catalyst has been reported. Treatment of the oxetane (341) with boron trifluoride etherate in diethyl ether leads to the ring expanded product (342). It is suggested that an intermediate carbocation is formed (Scheme 92) (79CC382). 

X-ray crystal structure studies have been reported for three oxetanes (4), 3,3-bis(trimethylaminomethyl)oxetane methanesulfonate and the 3,5-dinitrobenzoate ester of f/zreo- ,3,3,4,4-pentamethyloxetanemethanol (5). These compounds were all non-planar, with dihedral angles of 16, 29.4 and 8°, respectively (73CC34, 71DIS(B)(32)1445, 78CSC309). 

Ieptafluoro-propyl)-2,2,3.4-tetraHuoro-3-trifluoromethyl-EI0b, 511 (F"(, — pro-pen + RF —CO — F) 4-Mctliyl-2,.3,3-lrifluoro- E10b2. 116 (-HC1 Oxetane) 4-(Octanuoro-8I[-butyl)-2,2.3-(ri-nitoro-3-lnnuoromethyl- ElOb,. 511 t F - propen +... 

Some oxirane, oxetane, and oxolane derivatives of 1,6-anhydrohexoses are known, for example l,6 2,3-dianhydro-/i-D-allofuranose (165) and the corresponding a-L-talofuranose,243 1,6 2,5-dianhydro-a-L-gulofuranose (166),511,512 l,6 3,5-dianhydro-a-L-idofuranose,245 l,6 3,5-dianhydro-a-L-gulofuranose,246,512 and 1,6 4,7-dianhydro-D-g/ycero-/f-D-gulopyranose.249... 

A. Vargas-Berenguel, F. Santoyo-Gonzalez, J. A. Calvo-Asin, F. G. Calvo-Flores, J. M. Exposito-Lopez, F. Hernandez-Mateo, J. Isac-Garcia, and J. J. G. Martinez, Synthesis of 6-deoxyheptose derivatives via cyclic sulfates and oxetanes, Synthesis, (1998) 1778-1786. 

The biological and pharmaceutical properties of oxetanes have been highlighted throughout the chapter when other aspects such as their synthesis is described. For example, as discussed in Section 2.05.11, oxetanones form part of the structure of potent inhibitors of lipases and other enzymes. The naturally occurring amino acid oxetin is used as an antibiotic, and foldamers derived from analogues of oxetin have other potential therapeutic uses. The antiobesity drug tetrahydrolipstatin 119 was described in Section 2.05.11 and the /3-lactone F-244 (1223 A) has been reported with antibiotic properties <1998BMC1255>. 

This type of reaction has some precedence i.e., cyanohydrin formation (KCN, DMSO), followed by intramolecular displacement of a tosylate by the incipient alkoxide leads to the formation of a 2-cyano oxetane system. Furthermore, KCN in MeOH results in the addition of methanol across a nitrile group. Nerdel, F. Weyerstahl, P. Lucas, K. Tetrahedron Lett. 1965, 5751. 

The kinetics of the reaction is in agreement with a mechanism involving the formation of the biradical 6 following Scheme 3.6, where B is benzophenone, F is furan, (B-F) is the biradical 6, and Ox is the oxetane [28]. Subsequently, more complex carbonyl compounds were used to give the corresponding... 

Bertolini, F., Crotti, S., Bussolo, V.D., Macchia, F., and Pineschi, M. (2008) Regio- and stereoselective ring opening of enantiomerically enriched 2-aryl oxetanes... 

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