Pyridine aldehydes, synthesis

Prostaglandins 624, 725, 960 Prostanoids 620 Protonation 565-567, 1049 photochemical 882 Pseudopotential methods 15, 16 Pummerer rearrangement 240, 243, 470, 843 Pyramidal inversion 602, 604 Pyrazolenines 749 Pyridazine oxides 640 Pyridine aldehydes, synthesis of 310 Pyridine oxides 640 Pyrolysis 102-105 of sulphones 110, 679-682, 962 of sulphoxides 739, 740 Pyrroles 265, 744... 

Thieno[3,2-c]pyridine, 4,5,6,7-tetrahydro-biological activity, 4, 1015 Thieno[2,3-6]pyridine-2-carb aldehyde synthesis, 4, 1014... 

Roberge, C., Eleitz, E., Pollard, D. and Devine, P., Asymmetric synthesis of cyanohydrin derived from pyridine aldehyde with cross-linked aggregates of hydroxynitrile lyases. Tetrahedron Lett., 2007, 48, 1473-1477. 

Of the pyridine aldehydes, only Schiff s bases (192) from 3-formyl-pyridine and anilines such as p-chloroaniline, which with the stilbazole 190 forms l,4-bis[/3-(3-pyridyl)vinyl]benzene (193), have been found to undergo the Anil Synthesis.34... 

The classic Krohnke aldehyde synthesis results from the displacement of pyridinium salts aromatic nitroso compounds to give nitrones which are hydrolyzed to aldehydes.Phenacyl bromide reacts with pyridine and then nitrosobenzene to give phenylglyoxal in 76% yield after acid hy lysis. The pyridinium salts in these reactions must be activated in some way toward displacement to effect efficient conversions. 

Pyridine derivatives, synthesis from 2-methyleneglutaronitrile 81YGK813. Pyridines, synthesis from aldehydes and ammonia 75KGS1587. 

The Chi synthesis modulators that Rebeiz et al. (13, 14) used in conjunction with ALA could be divided into three categories A) enhancers of ALA conversion to porphyrins (2-pyridine aldoxime, 2-pyridine aldehyde, picolinic acid, 2,2 dipyridyl disulfide, 2,2 -dipyridyl amine, 4,4 dipyridyl, and phenanthridine), B) inducers of ALA biosynthesis and porphyrin accumulation (2,2 -dipyridyl and 1,10-phenanthroline), and C) inhibitors of MV PChlide synthesis (2,3-dipyridyl, 2,4-dipyridyl, 1,7-phenanthroline, and 4,7-phenanthroline). Compounds in group A did not cause significant porphyrin accumulation alone however, they enhanced dark conversion of exogenous ALA to porphyrins. This group was further subdivided into compounds that enhanced conversion of ALA to MV PChlide (2-pyridine aldoxime, 2-pyridine aldehyde, picolinic acid, and 2,2 -dipyridyl disulfide) and those that stimulated conversion to DV PChlide (4,4 dipyridyl, 2,2 dipyridyl amine, and phenanthridine). To qualify as an ALA biosynthesis and porphyrin accumulation inducer (category B), the compound had to cause these effects in the absence of ALA. Compounds in category C had to inhibit accumulation of MV PChlide with or without ALA. In most cases, in conjunction with ALA, the compounds stimulated DV PChlide accumulation compared to the ALA-treated control. 

The best method for synthesis of various pyridine aminophosphonates is a thermal addition of diethyl phosphonate to pyridine aldimines. Pyridine aldehydes react easily with aliphatic or aromatic amines in toluene solution to form corresponding aldimines (Schiff bases). The obtained imines were reacted in situ with diethyl H-phosphonate to give aminophosphonate diethyl esters [24],... 

Chichibabin (see Bodroux-Chichibabin Aldehyde Synthesis) Chichibabin Pyridine Synthesis Chichibabin Reaction Chloromethylation... 

Sodiiim phenylacetylene, reaction with p-nitrophenyl-propiolyl chloride, 615 Stilbazoles, -carboxy-prep-aration from pyridine aldehydes, 342, 343 stereochemistry, 342, 343 -cyano-preparation from pyridine aldehydes, 343 stereochemistry, 343 stereochemistry of, 348, 349 synthesis, 348, 349 Strecker reaction, preparation of 2-cyanomethylfurans, 666 Strecker synthesis, of pyri-dine-side chain nitriles, 362, 535-538 Streptonigrin, 626 Styryl isocyanates, reaction with ynamines, 639 6-Substituted-2,4-bis(alky 1-... 

Evaluation of the four routes discussed above revealed that the acyl anion addition provided the most convergent approach to this compound and was selected for further development. While the route disclosed in Scheme 5 provides the desired product in four steps, a more convergent approach may arise from introducing the amine side chain earlier in the sequence (i.e. in the pyridine aldehyde). Thus to optimize this route we would need to have a practical synthesis of 2-[(l-phenylethyl)amino]-4-pyridinecarboxaldehyde 19, optimize and understand the thiazolium catalyzed cross coupling process, and investigate the Cbz-deprotection and final salt formation... 

S.A. Siddiqui, T.M. Potewar, R.J. Lahoti, K.V. Srinivasan, Ionic liquid promoted facile one-pot synthesis of l-pyridylimidazo[l,5-aryl aldehydes. Synthesis (2006) 2849-2854,... 

Hantzsch synthesis The formation of pyridine derivatives by the condensation of ethyl acetoacetate with ammonia and an aldehyde. Also applied to similar syntheses of pyrroles. 

Another important reaction of diketene derivatives is the Hant2sch pyridine synthesis (101). This synthesis is the preparation of 1,4-dihydropyridines (14) starting either from two acetoacetic esters, which react with an aldehyde and ammonia or a primary amine or from 3-aminocrotonates and 2-alkyhdene acetoacetic esters, both diketene derivatives. Several such dihydropyridines such as nifedipine [21829-25-4] (102), nimodipine [66085-59-4] and nicardipine [55985-32-5] exhibit interesting pharmaceutical activity as vasodilators (blood vessel dilation) and antihypertensives (see Cardiovascularagents). 

The formation of pyridine derivatives from a, P-unsaturated aldehydes and ammonia involves formation of three bonds during the ring synthesis. For example, with an a, P-unsaturated aldehyde, both 2,5-substituted as well as 3,4-substituted pyridines can be obtained, depending on whether a 1,2- (eq. 17) or 1,4-addition (eq. 18) occurs with ammonia. Reactions are performed in the vapor phase with catalysts. 

By-Products. Almost all commercial manufacture of pyridine compounds involves the concomitant manufacture of various side products. Liquid- and vapor-phase synthesis of pyridines from ammonia and aldehydes or ketones produces pyridine or an alkylated pyridine as a primary product, as well as isomeric aLkylpyridines and higher substituted aLkylpyridines, along with their isomers. Furthermore, self-condensation of aldehydes and ketones can produce substituted ben2enes. Condensation of ammonia with the aldehydes can produce certain alkyl or unsaturated nitrile side products. Lasdy, self-condensation of the aldehydes and ketones, perhaps with reduction, can lead to alkanes and alkenes. 

Raw Material and Energy Aspects to Pyridine Manufacture. The majority of pyridine and pyridine derivatives are based on raw materials like aldehydes or ketones. These are petroleum-derived starting materials and their manufacture entails cracking and distillation of alkanes and alkenes, and oxidation of alkanes, alkenes, or alcohols. Ammonia is usually the source of the nitrogen atom in pyridine compounds. Gas-phase synthesis of pyridines requires high temperatures (350—550°C) and is therefore somewhat energy intensive. 

Paal-Knorr synthesis, 4, 118, 329 Pariser-Parr-Pople approach, 4, 157 PE spectroscopy, 4, 24, 188-189 photoaddition reactions with aliphatic aldehydes and ketones, 4, 232 photochemical reactions, 4, 67, 201-205 with aliphatic carbonyl compounds, 4, 268 with dimethyl acetylenedicarboxylate, 4, 268 Piloty synthesis, 4, 345 Piloty-Robinson synthesis, 4, 110-111 polymers, 273-274, 295, 301, 302 applications, 4, 376 polymethylation, 4, 224 N-protected, 4, 238 palladation, 4, 83 protonation, 4, 46, 47, 206 pyridazine synthesis from, 3, 52 pyridine complexes NMR, 4, 165... 

Pyrrolo[2,3-6]pyridine, 6-methyl-reaction with aldehydes, 4, 503 reaction with benzaldehyde, 4, 511 Pyrrolo[2,3-6]pyridine, 7-methyl-hydrogenation, 4, 508 Pyrrolo[2,3-6]pyridine, 3-nitro-2-phenyl-reduction, 4, 511 Pyrrolo[2,3-6]pyridine, 2-phenyl-nitrosation, 4, 506 quatemization, 4, 503 synthesis, 4, 522... 

One step synthesis o( substrtuted pyridines from a beta keto ester, an aldehyde arid ammonia. 

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