2,6,7-Trioxabicyclo 2.2.1 heptane

The checkers also prepared racemic 1-[N-benzyloxycarbonyl-(1 )-1-amino-2-hydroxyethyl]-4-methyl-2,6,7-trioxabicyclo[2.2.2]octane using the identical procedure (50% over 2 steps from racemic Cbz-serine purchased from Aldrich Chemical Company, Inc.). The enantiomeric ratio of the crystalline (S)-3 enantiomer (Note 20) was > 99.5 0.5 as determined by comparison with racemic 3 by courtesy of Mr. Eric Hortense (GlaxoSmithKline, Stevenage). Chiral HPLC (25 cm Chlracel OD-H, Column No ODHOCE-IF029, mobile phase ethanol/heptane 1 4 v/v, UV detector at 215 nm, flow rate... 

Preparation of 2,7,8-trioxabicyclo[3.2.1]octanes by the oxidation of 2,7-dioxabicyclo[2.2.1]heptanes with m-chloroperbenzoic acid [189]. 

Cyclic 1,2,4-trioxanes (14 and 15) have been obtained from the photosensitized oxidation of (urans. These compounds arc 2,3,7-trioxabicyclo [2.2.1] hept-5-ene (14) and 2,3,7-trioxabicycIo [2.2.1] heptane (15). 

Matsumoto, M., Watanabe, N., Kasuga, N.C., Hamada, F. andTadokoro, K. (1997) Synthesis of 5-alkyl-l-aryl-4,4-dimethyl-2,6,7-trioxabicyclo[3.2.0]heptanes as a chemiluminescent substrate with remarkable thermal stability. Tetrahedron Letters, 38 (16), 2863-2866. 

In marked contrast, bicyclic orthoesters are less reactive than another acyclic reference compound, trimethyl orthoformate. [79] For instance, the rate of hydrolysis of 2,6,7-trioxabicyclo[2.2.1]heptane (80) was slower by about 50% than that of trimethyl orthoformate. In addition, there are relatively small differences among the rate constants for the bicyclic orthoesters of [2.2.1]heptane, [3.3.1]no-nane, [3.2.1]octane and [4.2. l]nonane systems. This unexpected behavior was... 

Polymerization of 80 at — 78 °C gave a polymer consisting mostly of five-membered rings (81), which indicates that dominant cleavage takes place at the C(l)—0(2) bond. [81] l-Methyl-2,6,7-trioxabicyclo[2.2.2]heptane also gave a polymer, which was found to consist of five membered rings from 13C NMR spectra, contrary to an earlier report. [83]... 

Bicyclo [2.2.2] octane has the D3h or D3 symmetry (to lessen the repulsion of the eclipsing hydrogens at Q and C3, there is a slight rotation around the three fold axis) and its strain energy is slightly less than that of bicyclo [2.2.1] heptane (Table 4). The geometry may be preserved in 2-oxa-(II), 2,6-dioxa-(III), and 2,6,7-trioxabicyclo [2,2.2] octane (IV). Ill showed high reactivity in the polymerization and the acid-hydrolysis... 

Trioxabicyclo[2.2.1]heptane VIII gave five-membered units in the polymer chain56,57J. The selective formation of five-membered rings (or the selective cleavage at Ci-02 bond) indicates that one of intermediates is not reactive. 

Schuerch2) reviewed the medical application of synthetic poly-saccharides. Capozza199 reported that the poly-orthoester prepared from 2-ethoxy-4-hydroxymethyl-l,3-diox-olane in the presence of add are useful as slow-release agents for drugs. Poly-2,6,7-trioxabicyclo[2.2.1]heptane VIII showed the same behavior200). 

Upon an extensive study, we found a new chemiluminescence substrate for the enzyme iimnunoassay using a new 1,2-dioxetane derivative, 5-t-butyl-4,4-dimethyl-l-(3 -phosphoryloxy)phenyl-2,6,7-trioxabicyclo[3.2.0]heptane disodium salt as shown in Scheme l. °... 

Ethyl 3,3-diisopropyl-7-erccfo- and -7-e.To-methyl-2,4,6-trioxabicyclo[3.2.0]heptane-7-carboxylate22 is obtained from ethyl pyruvate and 2,2-diisopropyl-l,3-dioxole, ratio 7-CH3 endo/exo 4 1. The isomers are separated by flash chromatography (silica gel, EtOAc/cyclohexane 1 9). 

Phenylmcnthyl] 3,3-Dimethyl-7-phenyl-2,4,6-trioxabicyclo]3.2.0 heptane-7-carhoxylate (Table 6, Entry 4) Typical Procedure19 ... 

The polymerization of a bicyclic monomer, in which only one or both rings are opened has recently been reported by Hall47. This monomer 2,6,7-trioxabicyclo 2.2.11-heptane (TBH) may be prepared in 73 % yield by the reaction of glycerol and triethyl-orthoformate ... 

Bulk polymerization of 2,6,7-trioxabicyclo 2.2.1 heptane with 1 mol% CF3S03H initiator at 80 °C directly gives linear polymer with a quantiative yield (after 1 h). The structure of this polymer was determined from H-NMR spectra, which showed... 

Fig. 8.5. H-NMR spectra of poly-2,6,7-trioxabicyclo 2.2.1 heptane in CDC13. a — polymer obtained at — 78 °C b — polymer obtained at 80 °C or by heating polymer a with H0S02CF3 47 ...

---