Ethers.......................................................................................VIII

The flask was charged with 2.0 mol of dry, freshly distilled (note 1) methyl propargyl ether (VIII-6, Exp. 7), potassium iert.-butoxide (note 2) (5 g) was added with stirring and the mixture was heated under reflux. The reaction was... 

Propylpiperonyl) (benzyl) ether (VIII) Modification of toxophoric nucleus 26 6 25 1... 

The 3-enol ether (VIII) of 16-benzalandrostenedione (VII) was reduced selectively19 to the carbinol (IX). After reduction the 3-keto group was regenerated by treatment of the enol ether with acid. Another... 

According to that author, such a typical aromatic nitro compound as 4-nitro-1-naphthol (VII) when reacted with diazomethane, formed not only methyl ether (VIII) but also quinone oxime (IX) in lower yield (16%) ... 

When p-nitro-N,N-dimethylaniline (IVc) was ozonized at 0°C in ethyl acetate, methylene chloride, or methanol, a mixture of products resulted. In addition to the expected side-chain oxidation products— p-nitro-N-methylaniline (Vc), p-nitro-N-methyl formanilide (Vic)—a peroxide compound was formed. This peroxide, which is not formed until the solvents are removed, was shown by a series of experiments (described below) to be identical with di-[(N-methyl-p-nitrophenyl)-aminomethyl] peroxide (VII). Deoxygenation of VII with triethyl phosphite (7) yielded the ether VIII, which in turn decomposed at its melting point to the amine IX. 

Berbamine occurs in B. vulgaris, B. aquifolium (12, 13), B. thunbergii (22), Stephania cepharantha Hayata (23), and in B. swaseyi Buckley Mahonia swaseyi Fedde) to the extent of about 2 % in the dried roots (24). Santos (21) found that berbamine was isomeric with oxyacanthine and that oxidation of berbamine methyl ether produced 4, 5-dicarboxy-2-methoxy-diphenyl ether (VIII, R = CH3), as in the case of oxyacanthine. The constitution of the isoquinoline portion of the molecule was determined by von Bruchhausen, Oberembt, and Feldhaus (18). The products obtained after a Hofmann degradation of 0-methylberbamine followed by ozonization were the same two dialdehydes, XXXV and 4, 5-diformyl-2-methoxydiphenyl ether (XXXIV), as were obtained from 0-methyloxy-acanthine by similar treatment. On the basis of these facts von Bruchhausen and coworkers concluded that berbamine and oxyacanthine are structural isomers. If o.xyacanthine is assigned the formula XXVI then berbamine must have the formula XXXI or vice versa. 

The stability of the intermediate oxonium ions V and VII determine which of the two possible routes leading either to the phenolic species IV, or to the aromatic vinyl ether species VIII is preferred. In the case of an aliphatic group R, the oxonium ion V, stabilized by an aromatic system, is preferred over the aliphatic oxonium ion VII. This favors the cleavage to the phenolic compound IV but not the formation of the vinyl ether VIII. This vinyl ether reacts further to the symmetrical species III as depicted in Scheme 1. High catalyst concentration or high temperature causes the formation of the aromatic vinylether VIII to compete with the reaction leading to IV (42). In this case an intermolecular crosslinking between two polymer chains occurs. 

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