4,4 -dimethoxy-3,3 -dimethyl

Mit vielfach guten Ausbeuten verlauft die folgende, zweistufige Alternative zur Mannich-Reaktion, bei der ein Alkyl-keton zunachst durch Umsetzung mit Dimethoxy-dimethyl-amino-methan (oder auch mit Bis-[dimethylamino]-tert.-butyloxy-methan) in ein 1-Ami-no-3-oxo-l-alken iibergefuhrt wird, das isoliert und mit Lithium-alanat zum Mannich-Produkt reduziert wird2. 

A solution of 4% aq. H2SO4, (301) was heated to 50"C over 30-60 min. Nitrogen was bubbled through the solution during this time. 4-(Cyano-methyl)phenylhydrazine hydrochloride (1080g, 4.77 mol) was added as a solid to the heated mixture. After it had dissolved, A,A-dimethyl-4,4-dimethoxy-butanamine (965 g, 5.98 mol) was added over a period of 30 min. The mixture was then heated at reflux for 2 h. The reaction mixture was cooled and diluted with portions of 30%o aq. NH4OH (21 total) over 0.5 h at a rate to maintain the temperature at 25-30°C. The product was then extracted into isopropyl acetate (3 x 101). The solution was concentrated to 31 which led to a precipitate which was isolated by filtration and washed with cold isopropyl acetate to give 827.4 g (76%) of product. 

Benzo[b]furan-2-carboxylic acid, 3,6-dimethoxy-, methyl ester UV, 4, 589 <71AJC1883> Benzo[b]furan-2-carboxylic acid, 5,6-dimethyl-, methyl ester... 

Benzo[b]furan, 2,3-dihydro-2-phenyl-synthesis, 4, 697 Benzo[b]furan, 2,3-dihydroxy-tautomerism, 4, 37 Benzo[6]furan, 4,6-dimethoxy-acylation, 4, 606 Benzo[6]furan, 2,3-dimethyl-acetylation, 4, 606 bromination, 4, 605 photooxygenation, 4, 642 Benzo[b]furan, 5,6-dimethyl-2,3-diphenyl-applications, 4, 709 Benzo[b]furan, 1,3-diphenyl-vertical ionization potential, 4, 587 Benzo[b]furan, 2-ethoxy-5-hydroxy-synthesis, 4, 127... 

H-Chromene, 6,7-dimethoxy-2,2-dimethyl-application, 3, 881 2H-Chromene, 2,2-dimethyl-addition reactions, 3, 670 fluorinated... 

Purine, 1,6-dihydro-8,9-dimethyl-6-thioxo-synthesis, 5, 583 Purine, 2,6-dimethoxy-synthesis, 5, 596 Purine, 2,6-dimethoxy-7-methyl-rearrangement, 5, 558 Purine, 2,7-dimethyl-halogenation, 5, 547 Purine, 7,9-dimethyl-UV spectra, 5, 517 Purine, 8,8-dimethyl-synthesis, 5, 580 Purine, 6-dimethylamino-mass spectra, 5, 519 occurrence, 5, 600 Purine, 6-dimethylamino-9-benzyl-alkylation, 5, 531 Purine, 3,7-dimethyl-6,8-dioxo-methylation, 5, 534 Purine, 6,8-dioxo-alkylation, 5, 534... 

Pyridine, 2,6-dimethoxy-3-nitro-nitration, 2, 188 Pyridine, 2,3-dimethyl-synthesis, 2, 479 Pyridine, 2,4-dimethyI-acylation, 2, 333 alkylation, 2, 333 synthesis, 2, 479... 

Selenophene, 2,5-diamino-3,4-dicyano-synthesis, 4, 119, 964 Selenophene, 2,4-diaryl-synthesis, 4, 967 UV spectra, 4, 941 Selenophene, 2,5-diaryl-synthesis, 4, 967, 969 UV spectra, 4, 941 Selenophene, 2,5-dichloro-metallation, 4, 949 Selenophene, dihydro-3-methylene-synthesis, 4, 963 Selenophene, 2,5-dimethoxy-lithiation, 4, 949 Selenophene, 2,4-dimethyl-... 

Proof of formula (VI) for dehydrolaudanosoline salts was provided by a study of its exhaustive methylation, the products at the first and second stages of the application of this process being 5 6-dimethoxy-2-(3 4 -dimethoxy-6 -vinylphenyl)-l-methyldihydroindole (VIII) and 6-dimethyl-amino-3 4 3 4 -tetramethoxy-6 -vinylstilbene (IX) respectively. 

B. HCl, m.p. 242-3°). The methiodide, m.p. 104-7°, of this, on treatment with potassium hydroxide in methyl aleohol, yielded 5 6-pimethoxy-8-vinylphenanthrene, m.p. 86-7°, along with dimethyl-de-iV-methylnorroemerine, oil, [aju + 13-55° (EtOH) the methiodide, m.p. 278°, of this, on like treatment also yielded 5 6-dimethoxy-8-vinyl-phenanthrene, whose identity was established by its oxidation by permanganate to 5 6-dimethoxyphenanthrene-8-earboxylie aeid. Rcemerine is, therefore, 5 6-methylenedioxy-iV-methylaporphine, and this eon-stitution has been confirmed by Marion and Grassie s synthesis of the alkaloid. 

Another type of diazafulvalenes was obtained by the condensation of sodium cyclopentadienide with l,2-dimethyl-3,5-dimethoxy- and -3,5-bis(methylsulfanyl)pyrazolium salts (94AP385). Under mild conditions displacement of MeZ groups in each case led to the diazafulvalenes 58. A... 

The structures of 6,6-dimethyl-6,7-dihydropyrido[l,2-c]quinazolinium salt (142) (97AJC109), and 6-methyl-9,10-dimethoxy-4-phenyl-... 

It is quite feasible to run the reaction at a bath temperature of 90-95° by adding all reagents to the flask initially a quantitative evolution of carbon dioxide occurs over a period of about 18 hours. The reaction can also be carried out in refluxing 1,2-dimethoxy-ethane (Arapahoe Chemicals, Inc.) over a period of about 50 hours (yield 40-55%), or in triethylene glycol dimethyl ether (Ansul Chemical Company) at a bath temperature of 160° over a period of 2 hours (yield 64%). 

There have been very few examples of PTV derivatives substituted at the vinylene position. One example poly(2,5-thienylene-1,2-dimethoxy-ethenylene) 102 has been documented by Geise and co-workers and its synthesis is outlined in Scheme 1-32 [133]. Thiophene-2,5-dicarboxaldehyde 99 is polymerized using a benzoin condensation the polyacyloin precursor 100 was treated with base to obtain polydianion 101. Subsequent treatment with dimethyl sulfate affords 102, which is soluble in solvents such as chloroform, methanol, and DMF. The molar mass of the polymer obtained is rather low (M = 1010) and its band gap ( ,.=2.13 eV) is substantially blue-shifted relative to PTV itself. Despite the low effective conjugation, the material is reasonably conductive when doped with l2 (cr=0.4 S cm 1). 

Dimethyl l, 5-dimethoxy-3-methyl-3//-3-bcnzazepinc-2,4-dicarboxylate (mp 108-110 C) can be obtained in 31 % yield by the methylation of dimethyl l,5-dihydroxy-3-methyl-3A/-3-ben-zazepine-2,4-dicarboxylate (see Section 3.2.1.1.1.) with diazomethane.14... 

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