3- Ethoxycarbonyl-2-methylpyridine

An ANRORC mechanism has also been proposed (besides an inverse cycloaddition reaction) in the conversion of 1-methylpyrimidinium iodide into 3-ethoxycarbonyl-2-methylpyridine on treatment with ethyl -amino-crotonate (95RCB1272) (Scheme 23a). The reaction starts by addition of the -carbon of the crotonate at the electron-deficient 4-position of the... 

Chelated species are less common. The substituted thiourea 7V-ethoxycarbonyl-/V-[3-(/>-anisyl) pyrazol-5-yl]thiourea (eatu) acts as a monoanionic 0,S-chelate to cobalt(II), forming Co(eatu)2.506 Whereas ethylenethiourea (etu) has been observed to act as a S-donor monodentate in Co (etu)2X2(H20)2 (X = C1, Br), it binds as an S,N-chelate in Co(etu)2(OOCCH3)2.507 Both violet octahedral and blue tetrahedral cobalt(II) compounds Co(pptu)2Cl2 and Cp(pptu)Cl2 respectively were prepared with bidentate A -2-(5-pico 1 y 1)- A"-pheny 11hiourea (pptu) chelated.508 Refluxing Co powder with thiourea in 4-methylpyridine provides a route to isothiocyanates, which form by decomposition of thiourea to ammonium thiocyanate509 with one product, Co(pic)4(NCS)2, characterized by a crystal structure. 

Heating 6-[(2-carboxylphenyl)amino]-5-cyano-2-methylpyridine-3-carboxylate in refluxing POCI3 afforded 6-cyano-8-ethoxycarbonyl-9-methyl-ll//-pyrido[2,T3]quinazolin-ll-one, but in PPA at 135-145°C 2-methyl-3-ethoxycarbonyl-4-methyl-5-oxo-5,10-dihydrobenzo(3)-l,8-napthyridine-9-carboxylic acid formed <2004CHE510>. 

Ethoxycarbonyl moieties may be introduced at the benzylic position by reaction of pyridylmethyl anions with diethyl carbonate <1997S949> or ethyl chloroformate <2004BML1795>. Fries rearrangement of 0-(2-methylpyr-idyl)carbamates has been used to introduce an acetamide group to the benzylic position of 2-methylpyridines <1997SL839>. Treatment of O-pyridylmethylcarbamate 40 with 2.2equiv of LDA at —78 °C leads to the formation of pyridylacetamide 41 in 70% yield (Equation 30). 

In a follow-up study [34] it was discovered that the condensation of cyanothioacetamide with ethyl 2-ethoxymethylene-3-oxobutanoate in the presence of piperidine in fact gave a 41 % yield of 3-cyano-5-ethoxycarbonyl-6-methylpyridine-2(l//)-thione (III.92), and not the isomeric 4-methyl derivative as previously thought [32]. Methylation of (III.92) (Mel-KjCOj-DMF) followed by reduction (LiAlH4-Et20), methoxymethylation, and oxidation with w-chlorobenzoic acid led to the alcohol (III.98) (50%), the ether (Ill.lOO)... 

Dimethylaminoacryloyl)methoxy] -1 (2//)-phthalazinone (138) condensed with ethyl acetoacetate and ammonia (supplied as ACONH4) to give 4-[(5-ethoxycarbonyl-6-methylpyridin-2-yl)methoxy]-1 (2//)-phthalazinone (139) (reactants, AcOH, reflux, <2h 60%). ° " ... 

---