Methyl Enol Ethers Research Articles

Novel analgesics and molecular rearrangements in the morphine--thebaine group. XI. The base-catalysed rearrangement of dihydrothebainequinone.

The base-catalysed rearrangement of dihydrothebainequinone (4) proceeds differently from that of nepenthone (1; R = Ph) to give a phenolic diketone (6), hydrolysable to a triketone (7) and further rearranged by base to dihydroflavothebaone enol methyl ether (11).

Studies on making use of gamma-butyrolactone. XIV. Synthesis of furoquinoline alkaloid "pteleine"

A new furoquinoline alkaloid, pteleine3), was synthesized by the same route as the synthesis of previously reported furoquinoline alkaloids, i.e. dihydrodictamnine, dihydroevolitrine, kokusaginine, maculine, dihydroskimianine, and 7-hydroxy-8-methoxydihydrodictamnine, Condensation of 5-methoxy-2-nitrobenzoyl chloride and α-acetyl-γ-butyrolactone, in the presence of magnesium, gave 2-(5-methoxy-2-nitrobenzoyl)-γ-butyrolactone and catalytic reduction of its enol-methyl ether, obtained by treatment with diazomethane, afforded 2, 3-dihydropteleine. Bromination of 2, 3-dihydropteleine with N-bromosuccinimide and subsequent dehydrobromination gave pteleine.

Reaction of thebainone-A enol methyl ether with benzoquinone.

The reaction of thebainone-A enol methyl ether with benzoquinone involves a novel closure of the oxide bridge to give codeinone p-hydroxyphenyl methyl acetal. Hydrolysis of this adduct and of its dihydro-derivative gave codeinone and dihydrocodeinone respectively.

The reaction of phenylmagnesium bromide with 2-benzoyl-1-indanone and its enol methyl ether

Phenylmagnesium bromide undergoes conjugate 1,4-addition to 2-benzoyl-1-indanone and its enol methyl ether to give 2-benzoyl-3-phenylindene.

Photochemical transformations of dienes—VI : Photolysis of semicarbazone and oxime derivatives of 6-formyltestosterone methyl enol ether acetate

Irradiation of syn-semicarbazone enol ether (IV) in methanol with 2537Å light leads to a mixture of syn-ketal (VI) and anti-ketal (VII); anti-semicarbazone enol ether (V) is also formed. Irradiation of IV with 3500 Å light leads very rapidly to an almost quantitative conversion to anti-semicarbazone enol ether (V). It therefore seems that excitation of the long wavelength band (313 mμ) of IV gives rise to syn ⇋ anti isomerization, whereas the short wavelength band (228 mμ) is responsible for ketalization. Irradiation of syn-oxime enol ether (VIII) leads to syn-oxime ketal (XI), anti-oxime ketal (XII), nitrile enol ether (X) and nitrile ketal (XIII). The formation of the latter two compounds constitutes, to our knowledge, the first example of a photo-dehydration of oximes to nitrile. anti-Oxime enol ether (IX) could only be obtained upon irradiation of VIII with 3500 Å light.

Photochemical transformations of dienes—V : Photolysis of 6-formyltestosterone methyl enol ether acetate and related compounds

Irradiation of dienolether aldehyde (III) in methanol leads to the ketal aldehyde (V) which is further converted to ketal acetal IV and to III. The relative rate constants for these reactions have been determined, thus permitting exclusion of alternate reaction pathways.

γ-ブチロラクトンの利用研究 (第7報)

The new method for synthesis of dihydrodictamnine, reported in the preceding paper, was applied to the synthesis of other alkaloids of the furoquinoline series and a satisfactory result was obtained. Condensation of 4-methoxy, 4, 5-dimethoxy, and 4, 5-methylenedioxy derivatives of 2-nitrobenzoic acid with α-acetylbutyrolactone in benzene with magnesium as a catalyst afforded α-(o-nitrobenzoyl) butyrolactone which was treated with diazomethane, forming three kinds of enol-methyl ether. Catalytic reduction of these ethers afforded the corresponding 2, 3-dihydroevolitrine, 2, 3-dihydrokokusaginine, and 2, 3-dihydromaculine in a fairly good yield. Bromination of dihydrokokusaginine and dihydromaculine with N-bromosuccinimide and subsequent dehydrobromination afforded kokusaginine and maculine.