Shifts 1.5 -methoxy

Diastereomeric derivathation of a chiral alcohol (111) with an enantiopure compound such as Mosher s reagent [20445-33-4] (a-ttifluoromethyl-a-methoxy-a-phenylacetjichloride) (112) (91) results in two distinct compounds (113) and (114) with nonequivalent chemical shifts in the H-nmr spectmm (92). 

The empirical formula contains five double-bond equivalents. In the H NMR spectrum a doublet signal at Sh = 9.55 stands out. This chemical shift value would fit an aldehyde flinction. Since the only oxygen atom in the empirical formula is thus assigned a place, the methyl signal at Sh = 3.80 does not belong to a methoxy group, but rather to an /f-methyl group. 

METHOXYETHANOL (EGME) and 2-METHOXY ETHYL ACETATE (EGMEA) 2-Methoxyacetic acid in urine End of shift at end of workweek Nq... 

The methyl ester (100, R = CH3), derived from this A-nor acid by treatment with diazomethane, is different from the ester (102) obtained either by Favorskii rearrangement of 2a-bromo-5a-cholestan-3-one (101) or by the action of cyanogen azide on 3-methoxy-5a-cholest-2-ene (103) followed by hydrolysis on alumina. The ketene intermediate involved in photolysis of (99) is expected to be hydrated from the less hindered a-side of the molecule to give the 2j -carboxylic acid. The reactions which afford (102) would be expected to afford the 2a-epimer. These configurational assignments are confirmed by deuteriochloroform-benzene solvent shifts in the NMR spectra of esters (100) and (102). ... 

The largest shifts in frequency occur for methyl acetate, where the hydrogens in formaldehyde are replaced by a methyl group and a methoxy group, and most strikingly in acetyl chloride, where the hydrogen atom is replaced by a chlorine atom and a methyl group. 

The pyrimidine compounds are known to undergo a rearrangement of the 0-alkyl derivatives to the iV-alkyl ones. The methoxy derivatives of 1,3,5-triazine display a similar behavior. On applying methyl iodide to 2,4-dimethoxy-l,3,5-triazine one of the methyl groups is shifted giving rise to l-methyl-4-methoxy-derivative (22). This compound was also obtained by methylation of 4-methoxy-2-oxo-1,2-dihydro-1,3,5-triazine (18) with diazomethane. At higher temperature (100°C) in presence of methyl iodide a shift of both methyl groups takes place and methiodide is formed simultaneously (23). Similarly,... 

The ultraviolet absorption spectra of carboline derivatives have been repeatedly recorded. Since the basic jpyr-N in the carbohnes and in 3,4-dihydro-jS-carbolines is part of a conjugated system, protonation affects the electronic absorption spectra significantly. It is unfortunate therefore that the spectra of the protonated, as well as those of the unprotonated, species have not been reported in all instances. Protonation leads to a bathochromic shift of 20-30 mp,. This is illustrated by the absorption of j3-carboline, 1-methyl-jS-carboline, 7-methoxy-l-methyl-jS-carbohne, and the salts of these compounds. 

The ultraviolet absorption spectra of 3,4-dihydro-jS-carboline derivatives exhibit a dependence on pH similar to that shown by the speetra of the fully aromatie compounds. 3,4-Dihydro-/S-carboline and 1-methyl- and 7-methoxy-l-methyl-3,4-dihydro-jS-carbo-line serve as examples. The quaternary 3,4-dihydro-jS-earbolin-ium salts obtained on p /r-A-alkylation of these dihydro-j3-earbo-lines show a bathoehromic shift of 5 mp, eompared to the... 

Flash vacuum thermolysis (FVT) of 2-substituted 4//-pyrido[l,2-n]pyrimidin-4-ones 126 above 800 °C afforded (2-pyridyl)iminopropadie-none (130) (99JCS(P2)1087). These reactions were interpreted in terms of reversible ring opening of 4//-pyrido[l,2-n]pyrimidin-4-ones to imidoyl-ketenes 127. A 1,5-H shift in 127 generated the N(l)H-tautomeric methylene ketene 128, in which facile elimination of HX took place via a six-membered cyclic transition state 129 to yield 130. In the case of 2-methoxy derivative 126 (X = OMe) another competing pathway was also identified at lower temperature, which resulted in the formation C3O2 and 2-methylaminopyr-idine via mesoionic isomer 131 (Scheme 9). The products were identified by IR spectroscopy. 

R = Ar) and cyclized tricyclic compound 240 (R = Ar) was obtained when 2-bromoacetophenones were reacted with 8-hydroxyquinolin-2(l//)-one under the above conditions. Presence of a 4-methoxy substituent shifted the equilibrium to the ring-opened product 241 (R = 4-MeOPh), while that of 4-nitro group gave only cyclized product 240 (R = N02). Similarly, mixtures of ring-opened and 2,3,6,7-tetrahydro-5//-pyrido[l,2,3- /e]-l,4-benzoxazin-5-one derivatives were formed in the reaction of 8-hydroxy-l,2,3,4-tetrahydroquinolin-2-one and halomethyl ketones (00HCA349). 

Reaction products of concomitant anionotropic 1,3-shifts to nitrogen and 1,5-shifts to carbon of sulfonyl groups in azo coupling products ofa-methoxy /J-oxo sulfones have been found under thermal conditions55,56 (equation 14). 

The reaction of alkoxyarylcarbene complexes with alkynes mainly affords Dotz benzannulated [3C+2S+1C0] cycloadducts. However, uncommon reaction pathways of some alkoxyarylcarbene complexes in their reaction with alkynes leading to indene derivatives in a formal [3C+2S] cycloaddition process have been reported. For example, the reaction of methoxy(2,6-dimethylphenyl)chromium carbene complex with 1,2-diphenylacetylene at 100 °C gives rise to an unusual indene derivative where a sigmatropic 1,5-methyl shift is observed [60]. Moreover, a related (4-hydroxy-2,6-dimethylphenyl)carbene complex reacts in benzene at 100 °C with 3-hexyne to produce an indene derivative. However, the expected Dotz cycloadduct is obtained when the solvent is changed to acetonitrile [61] (Scheme 19). Also, Dotz et al. have shown that the introduction of an isocyanide ligand into the coordination sphere of the metal induces the preferential formation of indene derivatives [62]. 

The of 33 shows a bathochromic shift, compared to that of the corresponding spironaphthopyran [ max 531, 558(s) nm in toluene].78 The substituent effect in 2, 5, 6 - and 5-position of 33 on the absorption band of the colored form has been examined.72,77,7s The donor substituent group in 6 -position, such as piperidino group, gives a hypsochromic shift by 35 nm, but 5 -carbomethoxy substitution results in a bathochromic shift by 20 nm. This may be due to interaction between oxygen atom of the phenolate and methoxy group. 

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