Dihydro methine

Further degradation of 1-bromosinomeninone furazan methine yields l-bromo-9 10-dehydro-(—)-thebenone ketone furazan, which cannot be prepared by the bromination of [Lxxxvm] as this reaction gives the isomeric 9 -bromo-derivative. The Hofmann degradation of 1 9 -dibromosinomeninone furazan methine and the bromination of [Lxxxvm] and its 1- and 9 -bromo-derivatives all yield, finally, 1 9 -dibromo-9 10-dehydro-(—)-thebenone ketone furazan. l-Bromo-(—)-thebenone ketone furazan may be prepared either by the bromination of [lxxxix] or by the bromination of sinomeninone furazan dihydro-methine, followed by the degradation of the resulting 1-bromo-deriva-tive [51-52]. 

Dihydrosinomenilone dihydro-methine. 175 acetone plates -24-6 24 CHC0, 76... 

Rhodacyanines possess two chromophoric systems. They are at the same time neutrocyanine derivatives, which involves position 5 of the ketomethylene, and methine cyanine, which involves position 2. Following lUPAC s standard nomenclature rules, structure 7 is named 3-ethyl-4-phenyl-2- 4-oxo-3-ethyl-5-[2-(3-ethy]-2,3-dihydro-benzo-l,3-thiazo-lylidene)ethylidene]-tetrahydro-l,3-thiazolylidene-methyl -1.3-thiazolium iodide (Scheme 5). It implies that the 4-phenyl thiazole ring having the... 

This result was confirmed by cleavage of the double bond in XXIV to give the aldehyde XXV, in which the aldehydic hydrogen atom shows a 1 2 1 triplet at 9.83 S and therefore lies adjacent to a methylene group in position 6. Furthermore, isomerization of the methine XXIV with hydrochloric acid moves the double bond to the 6,7 position (XXVI) as shown by the appearance of an allylic methyl group in the NMR-spectrum (1.68 S, doublet, J = 2.6 c/sec), and in this compound (XXVI) there are two vinyl protons (multiplet at 5.47 S). The transformation of XXIV to XXVI does not involve rearrangement because both compounds on reduction yield the same dihydro derivative, XXVII. 

Using the same procedure, phenyl-substituted alkenes can be aminated. For example, the photochemically promoted reaction of l,2-dihydro-4-phenylnaphthalene (3) with an amine in the presence of 1,4-dicyanobenzene (/ -DCNB) afforded the corresponding 2-amino-1 -phenyl derivatives 4, albeit in relatively low yield after 64-71% conversion of the alkene30. The stereochemistry of the product is dependent on the steric bulk of the amine, since the intermediate benzylic carbanion should undergo protonation from the less hindered face, that is, opposite to the amino group. The stereochemical assignment of 4 was based on chemical shifts and coupling constants for the methine protons in the H-NMR spectra. 

A further correlation with a compound of known stereochemistry was achieved by Hofmann degradation of dregamine methiodide, which gave the methine (151) via its less stable A -isomer reduction of the ketone and ester groups, and formation of the cyclic ether (152) then afforded a compound identical with dihydro-taberpsychine methine (Scheme 17). In independent experiments it was established that C-16 had not suffered epimerization. ... 

Alkaline degradation of -codeine methiodide affords e-codeimethine [lxxxih], which resists isomerization [415, 428-9], and this on further degradation gives morphenol and acetylmethylmorphenol [428] (see Chap. VIII). Methine bases have also been prepared from i/r-codeine methyl ether [411, 419], dihydro-i/j-codeine-A [421] and its methyl ether [426], dihydro-i/j-codeine-B [421, 423], dihydro-i/f-codeine-C [295, 423] and its methyl ether [426], tetrahydro- -codeine [295] and its methyl ether [426]. 

Degradation of dihydro- -codeine-A [xxm] yields dihydro-e-codei-methine-A [xxrv], which can be reduced only to tetrahydro-e-codei-methine-A [xxn]. 

Similarly, treatment of dihydrocodeinone with lithium methyl affords 6-methyldihydrocodeine [xl], which can be degraded to 6-methyl-dihydrocodeine methine [xli] and 6-methyl-6-hydroxy-13-vinylhexa-hydromethylmorphenol [xin, R = CH=CH2], the latter giving 6-methyl-6-hydroxv-13-ethyloctahydromethyl morphenol [xim, 9 10-dihydro, R = Et] on reduction [70]. 

Ozonolysis op Dihydrocodeine Methine Rupture of the aromatic nucleus with production of an aldehydo-ester, 7 8-dihydrocodizal-3-methyl ester methine [lxix], occurs when dihydrocodeine methine [x] is treated with ozonized oxygen in aqueous acid solution. The hydroxyl group of [x] presumably remains intact, as an acetyl ester of [lxix] can be prepared, and oxidation with chromic acid leads to 6-keto-7 8-dihydrocodizonal-3-methyl ester methine [lxx] which no longer yields an acetyl derivative, [lxix] can be hydrogenated to a dihydro-derivative [87]. It is surprising that in the ozonolysis of dihydrocodeine methine rupture of the aromatic nucleus at the 2 3 bond occurs, whereas with dihydrocodeine rupture occurs at the 3 4 bond (see Chap. IV). 

As 6-chlorodihydrocodide cannot be hydrolysed [10] it is not surprising that it can be degraded to a-chlorodihydrocodeimethine-C [xxxvii] [20], The latter can be reduced to a-chlorotetrahydrocodeimethine [xxxvm, R = Cl], which is also accessible from a-tetrahydrocodei-methine [xxxvm, R = OH] [68]. Sodium-alcohol reduction of [xxxvm, R = Cl] affords a compound originally believed to be dihydro-desoxytetrahydrocodeimethine [xxxix], but subsequently shown to be unsaturated and to have the structure [xl] (dihydrodesoxycodeine-C dihydromethine) or that of the A6 7-isomer (dihydrodesoxycodeine-B dihydromethine) [29], The structure [xl] is preferable as it can arise from [xxxvm, R = Cl] by 1 4 reduction of the system... 

Dihydrodesoxycodeine-D [xm], the only non-phenolic dihydro-desoxycodeine, can be prepared by the catalytic hydrogenation of a-chlorocodide [rv] [29], /3-chlorocodide [v, It = Cl] [7, 29], bromocodide [v, R = Br] [29], and desoxycodeine-C [ix] hydrochloride [6], It has also been reported to be formed by catalytic reduction of codeinone oxime [xlii] hydrochloride [30]. Dihydrodesoxycodeine-D methine [xlhi] results from Hofmann degradation of the methiodide [7], and a substance that is presumably the dihydromethine [xliv] is obtained by catalytic reduction of a-chlorocodeimethine [xlv] [26]. 

Hydrogenation of thebainone-B methine proceeds rapidly, with the absorption of two moles of hydrogen and production of /S-dihydro-thebainone dihydromethine [xvin] [20-21] this is the only case in morphine series in which reduction of an 8 14 double bond results in configuration of the asymmetric carbon atom C-14 in the abnormal manner. The possibility of thebainone-B methine having the isomeric structure [xix] is ruled out by the ultra-violet absorption spectrum, which is closely similar to that of /S-codeimethine [xx] and dissimilar from that of a-codeimethine [xxi] (Kg. 9) [21]. 

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