Bicyclo 1-methoxy

X-r crystal structure determinations have been completed on two salts containing bicyclo[2.2.1]heptyl cations (Fig. 5.12). Both are more stable than the 2-norbomyl cation itself 18 is tertiary whereas 19 contains a stabilizing methoxy group. The crystal structure of 18 shows an extremely long (1.74 A) C—C bond between C-1 and C-6. The C(1)—C(2) bond is shortened to 1.44 A. The distance between C-2 and C-6 is shortened from 2.5 A in norbomane to 2.09 AThese structural changes can be depicted as a partially bridged structure. 

Methoxy-chinolyl-(4)-carbonyl]-5-vinyl- 63 6 9-Bora-bicyclo[3.3.1]nonan 7... 

Another synthesis using in situ-prepared o-benzoquinones has been reported by Liao and coworkers [45]. These authors observed that oxidation of 2-methoxy-phenols 7-92 with DAIB in the presence of unsaturated alcohols 7-93 furnish transient o-benzoquinone monoacetal intermediates, which easily undergo an intramolecular Diels-Alder reaction to provide bicyclo[2.2.2]octenones 7-94 with high regio- and stereoselectivity, as well as in acceptable yields (Scheme 7.25). 

Rh2(OAc)4-catalyzed decomposition of m-methoxy-substituted diazoketones 244 furnishes 6-methoxy-2-tetralones rather than the expected bicyclo[5.3.0]decatrienones. This demonstrates that the direction of ring opening in the norcaradienone intermediate 245 may well be influenced by the nature and position of a substituent. 

An electron-releasing methoxy group enhances the regioselective insertion of platinum into a cyclopropane ring of 3 to form the complex 4, suggesting the stabilization of the incipient cation 5 with the methoxy group [6]. This result is in contrast to complexation to only the olefinic moiety of bicyclo[4.1.0] hept-3-ene under identical conditions. (Scheme 2)... 

Reaction of A,A-dimcthylsullamoyl aziridines 323 and 325 with primary amines furnishes substituted 1,2,5-thiadiazolidine 1,1-dioxides 324 and 326, respectively, in a regioselective manner <06SL833>. Aziridine 325 is made from ( I /t,6,S ,Z)-bicyclo[4.2. l]non-3-en-9-one in two steps /V,/V-dimethylsulfamoyl imine formation using dimethylsulfamide and subsequent reaction with trimethylsulfoxonium ylide. The product from the reaction with 4-methoxy-benzyl amine can be subsequently manipulated (debenzylation and derivatization) to give the alternative nitrogen substitution pattern in a controlled manner. 

The thermolysis of the bicyclodiene 109 at 225 °C gives rise to equilibrium mixture of cyclooctatriene and its transformation products (see below)54. More recently the influence of a methoxy group on the thermal behavior of the bicyclo[5.1.0]octa-2,4-diene system was studied56. Heating of 8-ewdo-methoxydiene 115 in cyclooctane at 95 °C gaves rise to methoxy substituted diene 117 and not to the product 116 of butadienylcyclopropane rearrangement (equation 41). The thermolysis of the 8-exo-isomer 118 has taken place as an equilibrium reaction to give 6-ewdo-methoxy diene 119 (equation 42)56. These two reaction partners were separated by TLC. 

Other reagents used for reduction are boranes and complex borohydrides. Lithium borohydride whose reducing power lies between that of lithium aluminum hydride and that of sodium borohydride reacts with esters sluggishly and requires refluxing for several hours in ether or tetrahydrofuran (in which it is more soluble) [750]. The reduction of esters with lithium borohydride is strongly catalyzed by boranes such as B-methoxy-9-bora-bicyclo[3.3.1]nonane and some other complex lithium borohydrides such as lithium triethylborohydride and lithium 9-borabicyclo[3.3.1]nonane. Addition of 10mol% of such hydrides shortens the time necessary for complete reduction of esters in ether or tetrahydrofuran from 8 hours to 0.5-1 hour [1060],... 

Behenic acid Sd oil <0.5% ° Bicyclo(3.3.0)-octane, 3-7-dioxa, 2-(3-4-methylenedioxy-phenyl) - 6- (4-hydroxy-3 -methoxy-phenyl) Sd ° ... 

Also, the structure of 63 is better described as zwitterionic with a C-N bond length of only 1.651 A <2001J(P2)133> in the case of methoxy instead of NMe2, the MeO- C=S separation is longer (2.550 A) and the two substituents behave as normal /rm-substituents. Furthermore, the 2,6,9-trioxo-bicyclo[3,3,l]nona-3,7-diene moiety 64 has been structurally characterized as part of Pd(ii) complexes <2003JOM(676)93> and as a novel chiral spacer unit in macrocyclic polyethers <2002SMC383, 2004T2857>. 

There are few published H-NMR data for bicyclo[4.4.0]decanes (decalins) one paper describes effects of hydroxy and methoxy groups on chemical shifts346. 

Amino-ethyl)-3-hydroxy-l-methoxy-cyclohexen wird schon in der Kalte durch 20%ige Schwefelsaure unter Hydrolyse der Methoxy-Gruppe zu 7-Oxo-2-aza-bicyclo [3.3. l]nonan cyclisiert3. 

TS 2 3,5-Dioxa-l-aza- bicyclo[4.2.0]octane 2,4-Dicyanomethylene-6- methoxy-7,8-tetramethyl 42 75JOC2552... 

Bicyclo[4.2.0]octan-7-ones 7, substituted at C8, resulted from addition of 7-lithio-7-methoxy-bicyclo[4.1.0]heptane to saturated and unsaturated aldehydes and subsequent rearrangement.146148... 

The double bonds in 2,3-dihydro-l,4-dioxin, 2,3-dihydro-l,4-oxathiin and 2,3-dihydro-1,4-dithiin undergo standard electrophilic addition reactions. Under acid catalysis, methanol adds to 2,3-dihydro-l,4-oxathiin to give 2-methoxy-1,4-oxathiane (66HC(21-2)842). Various examples are available of reactions of the double bonds with carbenoids to give bicyclo[4.1.0]diheteroheptanes (77LA910,78ZC15), and with alkenes in [2 + 2] cycloadditions (78CB3624). 

Halogenation of complex XXII afforded a mixture of 2-endo-methoxy-6-halo-ds-bicyclo[3.3.0]octane epimers, XXIVa and XXIVb (Table VI). In methanol, 2,6-endo,endo-dimethoxy-cis-bicyclo [3.3.0] octane, XXV, was obtained in addition to XXIV. The presence of halide ions suppressed the formation of XXII and favored that of XXIVb. Control experiments showed that both XXIV and XXV were primary products and did not... 

Plat ill (i/, -Bicyclo[2.2.1Jheptadien)-chloro-(4-methoxy-tetraflitoro-phenylF ElOb,. 426 (Cl -> Ar)... 

Decomposition of l-diazo-4-arylbutan-2-ones offers a direct entry to bicyclo[5.3.0]decatrienones and the approach has been extensively used by Scott and coworkers to synthesize substituted azulenes.137 Respectable yields were obtained with copper catalysis,137 but a more recent study24 showed that rho-dium(ll) acetate was much more effective, generating bicyclo[5.3.0]decatrienones (154) under mild conditions in excess of 90% yield (Scheme 34). The cycloheptatrienes (154) were acid labile and on treatment with TFA rearranged cleanly to 2-tetralones (155), presumably via norcaradiene intermediates (156). Substituents on the aromatic ring exerted considerable effect on the course of the reaction. With m-methoxy-substituted systems the 2-tetralone was directly formed. Thus, it appeared that rearrangement of (156) to (154) was kinetically favored, but under acidic conditions or with appropriate functionality, equilibration to the 2-tetralone (155) occurred. 

Several articles have been published on the intramolecular ortho photocycloaddition of substituted 4-phenoxybut-l-enes [104,105,164-166], In most cases studied, ortho adducts are converted into derivatives of bicyclo[4.2.0]octa-2,7-di-ene. This was also found [113] for ortho adducts derived from ort/ro-methyl- and ortto-methoxy-3-benzyloxyprop-1 -cries. In these cases, the angular products are formed exclusively, which is attributed to steric properties of the cyclooctatriene. 

Fig. 31. H CIDNP spectra (90 MHz) observed during the photoreaction of chloranil with the 6-methoxy-5-methylene-l, 2,3,4,6-pentamethyl-bicyclo[2.2.0]hex-2-ene (94) (0.02 M each in acetone-d6). The bottom trace is a dark spectrum...

Recently, the reaction of masked ortho-benzoquinone [92] with C60 was tested [93]. The [4+2] cycloaddition reaction of such electron-deficient dienes with fullerenes resulted in the formation of highly functionalized bicyclo [2.2.2] octenone-fused fullerenes. The reactants were generated in situ by the oxidation of the readily available 2-methoxy phenols with hypervalent iodine agents. For the several different masked ortho-benzoquinones that were tested, it was found that the yield of the cycloadducts depends on the nature of the starting materials and the reaction conditions. Other Diels-Alder reactions of such electron-deficient dienes with electron-poor fullerenes involved tropones [94], 1,3-butadienes substituted with electron-withdrawing groups [95], and 2-pyrone [96]. 

In a similar heterocyclic quinodimethane ring construction strategy, the hexacyclic adducts (64) were isolated in good yield upon condensation of appropriately functionalized indole imines with ( )-bicyclo[2.2.1]hept-5-ene-2-carboxylic acid chloride (Equation (35)) (88JA2242). In a demonstration of the utility of this new method for indole alkaloid synthesis, further transformations conducted on compound (64 R = R2 = H, R3 = Et) were shown to lead to ( —)-16-methoxy-tabersonine. 

Isopropylmagnesium bromide (2.5 m in ether, 0.36 ml) is added to a solution of (lS,2R,4R)-2-(2-methoxyethoxy)methoxy)-6-methylene-bicyclo[2.2.2]octane (68 mg, 0.3 mmol) in toluene (2.0 ml). The mixture is heated under reflux for 15 min (during which time a white precipitate forms). The mixture is cooled to room temperature, and water (10 ml) is added. The product is isolated via ether extraction (X3), chromatography and Kugelrohr distillation (150-160°/30 torr) as a colourless oil (47.2 mg, 81%). 

Other examples are the photocyclization of suitably substituted W-methyl-N-aryl-enamins (Scheme 8), which may undergo rearomatization [115] (44 gives 0.2% ee in the product 45) or the internal cyclization of 2-methoxytropone 46 which results in the bicyclic ketone l-methoxy-bicyclo[3.2.0]hepta-3,6-dien-2-one (l-CH30-22) [116]. 

---