2-Methyl-7-oxabicyclo- heptane

The dicarboxylation of cyclic alkenes is a useful reaction. All-c.vo-methyl-7-oxabicyclo(2.2.1]heptane-2,3,5,6-tetracarboxylate (233) was prepared from the cyclic alkene 232 using Pd on carbon and CuCh in MeOH at room temperature with high diastereoselectivity[216]. The dicarbonylation of cyclopentene... 

The knowledge of the valence tautomerization of benzene oxides to oxepins12 prompted several groups to synthesize oxepins by dehydrohalogenation of 7-oxabicyclo[4.1.0]heptane derivatives. Numerous examples have been described for the base-catalyzed elimination of hydrogen bromide from the 3,4-dibromo-7-oxabicyclo[4.1.0]heptane system. The reaction products are usually obtained as mixtures of oxepin 1 and benzene oxide 2. The 2,7-bis(hydroxy-methyl)oxepin 1 p obtained by this route can be converted to the 2,7-dicarbaldehyde with man-ganese(IV) oxide.23... 

Enthalpy of Polymerisation of Endo-2-Methyl-7-oxabicyclo [2.2.1] heptane, F. Andruzzi, D.S. Barnes and P.H. Plesch, Die Makromolekulare Chemie, 1975,... 

The copper-catalyzed photobicyclization of acyclic 1,6-dienes to bicyclo[3.2,0]heptanes using the bis[copper(l) lrifluoromethanesulfonate]benzene complex has found general and synthetic utility in the conversion of diallyl and homoallyl vinyl ethers to 3- or 2-oxabicyclo[3.2.0]heptanes,5 6 of /V-allyl-A -2-methyl-2-propenecarbamates to iV-carboethoxy-3-azabicyclo[3.2.0]heptanes 7 and of allylic alcohols to the corresponding hydroxy-substituted bicyclo[3.2.0]heptanes.8 9 Examples of such reactions are summarized below. 

Systematic name. 4-Methyl-7-oxabicyclo[4.1.0]heptane-3-carboxylic acid, 4-mctliyl-7-oxabicyclo[4.1.0]hept-3-yl methyl ester... 

OXABICYCLO(4.1.0)HEPTANE-3-CARBOXYLIC ACID. 4-METHYL-. ALLYL ESTER... 

OXABICYCLO(4.1.0)HEPT-3-ENE-2,5-DIONE. 3-HYDR0XY-4-METHYL-7-OXABICYCLO (4.1.0) HEPTANE, 3- (EPOXYETHYL) -7-OXABICYCLO(4.1.0)HEPT-3-ENE 1,3-OXATHIOLANE, 5- (CHLOROMETHYL) -... 

A number of pyrans, including 3-hydroxy-tetrahydropyran (both axial conformer, 29 and equatorial conformer, 30), 2-methoxy-tetrahydropyran 33, 3-methyl-tetrahydropyran 32, and several 4-substituted tetrahydropyrans, along with 2-methyl-l,3-dioxolane and the rigid cyclic ethers 7-oxabicyclo[2.2.1]heptane and 1,8-cineole, were studied extensively by NMR. These empirical results, in conjunction with the literature data for a variety of acyclic and cyclic ethers, were used to examine the reliability of O-substituent chemical shift models in these systems. The empirical data correlate well with predictions made from the model and it is concluded that ethereal oxygen substituent chemical shifts are due to both steric and electrostatic terms <1998J(P2)1751>. 

EPOXY-3-ISOPROPOXYPROP. NE see IPDOOO 4-(l,2-EPOXY-l-METHYLETHYL)-l-METHYL-7-OXABICYCLO(4.1.0)HEPTANE see LF 000 a-P-EPOXY-P-METHYLHYDROCINNAMICACID, ETHYL ESTER see ENCOOO... 

Fig. 1. Enthalpy change for the polymerization and depolymerization of exo- and endo-2-methyl-7-oxabicyclo[2.2. l]heptanes...

MOBH = 2-methyl-7-oxabicyclo[2.2.1]heptane, BOBH = 2-tert-butyl-7-oxabicyclo[2.2.1]hep-tane, and OBCO = oxabicyclo[3.3.1]octane... 

IS,4R)-4-isopropyl-l-methyl-7-Oxabicyclo[2.2. t]heptan-2-une yield 1.9% 13 1-isopropyl-4-methyl-7-oxabicyclo[2.2.l]heptan-2-ol yield not reported... 

Oxirane, 2-methyl-3-phenyl-, (2R,3R)- and 7-Oxabicyclo[4.1.0]heptane,l-phenyl-... 

In the photopolymerization of methacrylamide by benzoin methyl ether, chain-transfer to monomer has been found to be important, and benzalde-hyde is reported to be an inefficient photoinitiator of methyl methacrylate polymerization unless benzophenone and triethylamine are present. Acetophenone has been found to sensitize the cycloaddition of maleic anhydride to 7-oxabicyclo[2.2.1]heptan-5-one-2,3-dicarboxylic anhydride, , a-hydroxy-acetophenone derivatives have been found to be non-yellowing initiators, and h.p.l.c. has been used to determine residual carbonyl photoinitiators in u.v.-cured resins. In the emulsion-polymerization of methyl methacrylate using an aromatic ketone and a continuous or intermittent laser, the former conditions were found to be similar to those under continuous u.v. irradiation. The dependence of the polymerization rate and average chain-length on the absorbance of the initiator used in the photoinitiated polymerization of vinyl monomers has been studied. Interestingly, irrespective of all conditions, maximum conversion is observed when initiator absorbance is 2.51. "... 

Small molecule epoxides, and some epoxy oligomers also are used as reactive diluents, mixing them with other polymers for crosslinking purposes. An example of epoxide used as curing additive is poly(limonene dioxide) or poly[1-methyl-4-(2-methyloxiranyl)-7-oxabicyclo[4.1.0]heptane], CAS 29616-43-1. This compound can form ether bonds upon heating or by photoinduction in the presence of aryl substituted sulfonium salts. Poly(dicyclopentadiene dioxide), CAS 29987-76-6, has similar properties. The idealized structure of the two monomers with the intact epoxy groups are shown below ... 

To investigate the source of the unexpected cyclization, we combined a precursor 28 that did not have a 4-hydroxy group with the same stable ylide. This produced compound 29 with an oxabicyclo[2.2.1]heptane skeleton via the epoxide 30. Alternatively, the morphinan methyl ether 28 could also react with the stable sulfur ylide derived from trimethylsulfoxonium iodide at room temperature. The definitive intermediate, 6a-epoxide 30, was isolated, and then treated with NaH in DMF at 80 °C to produce the objective bicyclic compound 29 (Scheme 9). 

Hydrolysis of ( —)-methyl (15,3S)-(2,2-dimethyl-3-tosyloxycyclobutyl)acetate, obtained by a stereocontrolled route from (-f )-a-pinene, with zinc(II) acetate in aqueous dimethoxyethane at 80 °C leads to optically active 5-lactone ( —)-(lS,65)-2,2-dimethyl-3-oxabicyclo[4.1.0]heptan-4-one (1) in 62% yield.In addition to this cyclopropane derivative, a carboxylic acid was isolated which on treatment with diazomethane gave (-f )-methyl (5,5-dimethyl-2-tetrahydrofuryl)acetate (2). 

In order to relate these observations to the extensive information available on the mechanistic and stereochemical consequences of solvolytic tosyloxycydobutane rearrangements, the hydrolysis was performed in aqueous 1,2-dimethoxyethane at 80°C. The optically active (5-lactone ( —)-(15 ,65)-2,2-dimethyl-3-oxabicyclo[4.1.0]heptan-4-one (21) was isolated in 60% yield as the only neutral component. By acidification of the remaining aqueous phase, extraction, and methylation with diazomethane, (-h )-methyl 5,5-dimethyltetrahydrofurylacetate (22) was obtained. ... 

To a solution of 7,7-dichloro-3-methoxy-3-methyl-2-oxabicyclo[4.1.0]heptane (1.00 g, 48 mmol) in acetone (10 mL) was added 0.5 M H2SO4 (0.1 mL). After stirring for 30 min, the mixture was poured into sat. NaHCOj and extracted with EtjO. The organic phase was washed with brine and dried (MgS04), and the solvent was removed in vacuo yield 840 mg (93%). 

Cyclopropyl ketones have been converted into alkyl cyclopropanecarboxylates using various oxidizing agents. Peracids, such as peracetic acid, 3-chloroperoxybenzoic acid, and tri-fluoroperacetic acid, have been most frequently utilized, ° but the reaction has also been carried out photochemically. A severe problem can be concomitant formation of cyclopropyl carboxylates exo-4-trideuteriomethylbicyclo[3.1.0]hexan-2-one reacted with 3-chloroperoxybenzoic acid to give a significant amount of exo-5-trideuteriomethyl-2-oxabicyclo[4.1.0]heptan-3-one (12%) in addition to exo-5-trideuterio-methyl-3-oxabicyclo[4.1.0]heptan-2-one (49%). - ... 

---