Ethers bridged-ring

Annotinine, C gHjjOjN, (1). M.p. 232° perchlorate, m.p. 267°. In a later paper (1947) Manske and Marion record the results of the action of alkali and of halogen acids on annotinine, and of the oxidation of the base and discuss the reaction products. They conclude that two of the oxygen atoms are present as a lactone group and that the third oxygen may form an ether bridge in a 5- or 6-membered ring. 

The second step is the condensation reaction between the methylolphe-nols with the elimination of water and the formation of the polymer. Crosslinking occurs hy a reaction between the methylol groups and results in the formation of ether bridges. It occurs also by the reaction of the methylol groups and the aromatic ring, which forms methylene bridges. The formed polymer is a three-dimensional network thermoset ... 

Oxidative caibon-carbon bond formation from laudanosine derivatives generally favours a 6-membered ring. Severe steric constraints result in exceptions to this rule. Oxidation of the bridged ether derivative 34 results in carbon-carbon bond formation to form a 5-membered ring product and this process has been used for one stage in the synthesis of erythrina alkaloids [138]. Some of the morphinadie-none system is also formed, in spite of the steric constraint imposed by the ether-bridge. 

Phenol-formaldehyde prepolymers, referred to as novolacs, are obtained by using a ratio of formaldehyde to phenol of 0.75-0.85 1, sometimes lower. Since the reaction system is starved for formaldehyde, only low molecular weight polymers can be formed and there is a much narrower range of products compared to the resoles. The reaction is accomplished by heating for 2 1 h at or near reflux temperature in the presence of an acid catalyst. Oxalic and sulfuric acids are used in amounts of 1-2 and <1 part, respectively, per 100 parts phenol. The polymerization involves electrophilic aromatic substitution, first by hydroxymethyl carboca-tion and subsequently by benzyl carbocation—each formed by protonation of OH followed by loss of water. There is much less benzyl ether bridging between benzene rings compared to the resole prepolymers. 

The complex of 11 with the short chain guest propanediammonium picrate has a relatively low because the guest cannot stretch in the cavity and coordinate to both crown ether rings simultaneously. For the longer chain picrate salt (n = 4), the crown ether bridges must fold slightly toward each other... 

Some unusual nucleophile functional groups that have been utilized in cyclofunctionalizations to form bridged ring systems include cyclic hemiacetals (equation 18)73 and epoxides (equation 19).87 The cyclizations in equation (20) involve a cyclic enol ether as the reactive ir-system and have been used in syn-... 

Hymenocardine (58), (32, 40) has a p-hydroxy-w-aminoacetophenone unit (81), instead of the usual styrylamine, in its cyclic system which can be recognized in addition to N,N-dimethylisoleucylvaline and tryptophan in its acid hydrolysate. Mild alkaline hydrolysis results in ring opening via /3 elimination on the hydroxyamino acid and severance of the phenolate to a tetrapeptide 82 whose structure was determined by mass spectrometry and further hydrolysis. It is the only peptide alkaloid in which /3-hydroxy valine is involved in the aryl ether bridge. 

The term promorphinane compounds is used for bases without an ether bridge between the rings A and D of the morphinane skeleton. 

Two new alkaloids, atalanine (C34H30O9N2 mp 216-217°) (14) and ataline (C3aH3409N2 mp 209-210°) (15) were obtained. They represent a new type of acridone base in which two acridone rings are joined by an ether bridge. Mass spectral data supplemented by other physical measurements and by analogy with other natural aeridones served to provide the given structures (14). 

Cyclic mixed acetals with pendant diazo ketone side-chains undergo rearrangement to ether-bridged cycloheptane ring systems on treatment with Cu(hfacac)2.118 A Stevens [1,2]-shift of an oxonium ylide gives the major product (62), in some cases accompanied by minor amounts of a product (63) resulting from a [l,2]-shift of a sulfonium ylide. 

Soil. DT50 (field) 123 194 days (biphasic) nonleaching. The main metabolite in the soil (also classed as nonleaching) was formed by hydroxylation at the 3-position of the quinoline ring a minor metabolite (DCHQ), formed by cleavage of the ether bridge, was observed, especially in acidic soil... 

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