2-Methyl-1 //-pyrrolo pyridine

Pyrrolo[2,3-t)]pyridine, methyl-fat least 4 methyl isomers other than the 1- and 2-methyl- compounds XVII.E-6... 

Pyrrolo[2,3-6]pyridine, 2-methyl-Reimer-Tiemann reaction, 4, 508 Pyrrolo[2,3-6]pyridine, 4-methyl-hydrogen exchange, 4, 502 reaction with aldehydes, 4, 503 reaction with benzaldehyde, 4, 511... 

Pyrrolo[3,2-6]pyridine, 2-methyl-synthesis, 4, 527 Pyrrolo[3,2-c]pyridine, 4-amino-nucleophilic reactions, 4, 507 Pyrrolo[3,2-c]pyridine, 2,3-dihydro-reactions, 4, 512... 

The derivative from an isomeric fused system has been described as a sedative-hypnotic compound. The synthesis starts by condensation of the aminopicoline 32 with the haloketone 33. The resulting pyrrolo[l,2-a]pyridine 34 then undergoes a Mannich reaction with formaldehyde and dimethylamine to give the aminomethylated derivative 35. After quatemization of the di-methylamino group in 35 with methyl iodide, the ammonium group is displaced by cyanide to... 

V-Methyl-A/-(3-pyrrolyi)aminomethylenemalonates (893, R1 = Me) were cyclized by heating in polyphosphate at 95-100°C for 1.5-2.5 hr to afford pyrrolo[3,2-b]pyridine-6-carboxylates (895) in 50-72% yields (85JHC83). 

Pyrrolo[3,2-f]pyridine can be readily substituted with a variety of electrophiles at C-2 or C-3 after protection of the ring nitrogen atom. Derivatives can be synthesized with substituents such as iodo, methyl, trimethyltin, formyl, and allyl groups. The reactions proceed with excellent yields (47-95%) <200583581 >. 

DaB bei dieser Cycloadditionsreaktion auch das Aiken nicht beliebig gewahlt werden kann, zeigt die Reaktion des Iminium-ylids mit l-Methyl-l,2,3,6-tetrahydro-pyridin, die nur in maBiger Ausbeute zu einem Gemisch von 2,5-Dimethyl-octahydro-(pyrrolo[3,4-c]pyridiny und 1,4-Dimethyl-piperazin fiihrt2 das letztere Produkt bildet sich auch in an-deren Fallen durch Cyclodimerisierung des Iminium-ylids. 

Pyrrolopyridines are quaternized at the pyridine nitrogen by methyl iodide (often at room temperature). Sodium hydroxide treatment of the methiodide of pyrrolo[2,3-6]pyridine gives a stable free base which reacts with a second molecule of methyl iodide, this time at the pyrrole nitrogen (Scheme 4). The resonance stabilization of the free base is shown by its stability towards boiling 20% sodium hydroxide, which rapidly hydrolyzes l-methyl-2-pyridoneimine (55JA6554). The same procedure with S-carboline leads to the 1,5-dimethyl quaternary salt (19) which on pyrolysis yields the 5-methyl derivative (20 Scheme 5) (60CJC2152). 

Other products from pyridine and its 3- and 4-methyl and 3,5-dimethyl derivatives and MP are cyclazines (e.g., 100),291 which are probably formed from indolizines of type 97 by further reaction with MP and subsequent aromatization. This type of reaction has been achieved by heating appropriate indolizines with DMAD293 or MP in the presence of palladized charcoal, and the direction of the addition, as shown below, has been established in several instances.294 Heating MP with diethyl-2-pyridylmethylene malonate gave the pyrrolo[2,l,5- /]indolizine corresponding to 100, no trace of the expected indolizine intermediate (cf. 97) being observed.292... 

Methylphenanthridine with DMAD in benzene yields the 9a-methyl-9ai/-quinolizine (cf. 306, Section V,G,2) and a cyclobuta[4,5]-pyrrolo[l,2-/]phenanthridine (cf. 312, Section V,G,2) DEAD in ether gives the corresponding cyclobuta derivative, whereas 6-ethylphenan-thridine with DMAD in acetonitrile yields only the quinolizine as isol-able product. With MP, phenanthridine, like pyridine, yields indolizines,... 

Methoxycarbonyl methyl-1 //-pyrrolo 3,4-r pyridine-l,3(2//)-dione (47) has been reported to undergo ring expansion to afford methyl 4-hydroxy-1-oxo-l,2-dihydro-2,7-naphthyridine-3-carboxylate (48) (MeONa/MeOH, 100°C ... 

Reaction of l-(3,4-dimethoxybenzyl)-9-hydroxy-l,2,3,4-tetrahydro-8//-pyrido[l,2-a]pyrazin-8-one with 37% formaldehyde solution gave a tetracyclic tetrahydroprotoberberine analogue in a Mannich-type reaction (78AJC187). Reactions of 2,3,4,4a,5,6-hexahydro-l//-pyrazino[l,2-a]-quinolines with 1 W-pyrrolo[2,3-h]pyridine in the presence of 37% aqueous CH20 and AcONa in AcOH, and with 3-dimethylaminomethyl-l //-pyrrolo[2,3-h]pyridine afforded 3-[(l//-pyrrolo[2,3-h]pyridin-3-yl)methyl] derivatives (94MIP6 96USP5576319). 

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