282723-20-0Relevant academic research and scientific papers
Regioselective Amination or Alkoxylation of Halogenated Amino-, Thio- or Alkoxypyridines via Pyridyne Intermediates
Djukanovic, Dimitrije,Heinz, Benjamin,Idriess, Mohamed,Knochel, Paul,Martin, Benjamin,Siemens, Fiona
, (2021/11/26)
The treatment of 3-halopyridines (Cl, Br) bearing an R-substituent in position 2 (R = OEt, NEt2, N-piperidyl, or SEt) or in position 5 (R = OMe, OEt, SEt, NMe2, NEt2, or aryl) with KHMDS and an amine at 25 C for 12 hours in THF provided regioselectively 3
Regioselective syntheses of 2,3-substituted pyridines by orthogonal cross-coupling strategies
Koley, Moumita,Wimmer, Laurin,Schnuerch, Michael,Mihovilovic, Marko D.
supporting information; experimental part, p. 1972 - 1979 (2011/04/27)
2-Aryl/alkylamino-3-aryl I and 3-aryl/alkylamino-2-aryl pyridines II, as important potentially bioactive compounds, were synthesized by applying orthogonal cross-coupling strategies. Combinations of the Suzuki-Miyaura, Liebeskind-Srogl, and Buchwald-Hartwig protocols gave access to the title compounds in a straightforward and operationally simple manner. Full control over the regioselectivity at the 2- and 3-positions was achieved by using 2,3-dichloropyridine or 3-iodo-2-(methylthio)pyridine as simple, commercially available starting materials. Within this contribution, efficient and high yielding conditions were developed for the Suzuki-Miyaura cross-coupling reaction of 2-substituted 3-chloropyridines, a transformation formerly underrepresented in the literature. For the synthesis of 3-alkyl/arylamino-2- aryl pyridines, the stability of the methylthio group was exploited under Pd-catalysis in the absence of a copper source. This even enabled the development of an operationally highly facile (semi)-one-pot protocol to access the aforementioned compound class that avoided one purification step. A series of products I and II was prepared by using the developed protocols with excellent regioselectivity and good yields. Copyright
Nucleophilic substitution reaction of amines with 3-bromo-4-nitropyridine (and 2-nitropyridine): A new nitro-group migration
Yao, Jiangchao,Blake, Paul R.,Yang, Ji
, p. 2071 - 2081 (2007/10/03)
On the reaction 3-bromo-4-nitropyridine with amine, three in stead of two expected products are separated. 2D NMR spectral data indicate the major product was an unexpected nitro-group migration product. To explore the rearrangement mechanism, a systematic study with various solvents and bases was undertaken. Results obtained indicate that nitro-group migration occurs in polar aprotic solvents; while expected nucleophilic substitution took place under all tested conditions.
Substituted 3,4-pyridynes: Clean cycloadditions
Connon, Stephen J.,Hegarty, Anthony F.
, p. 1245 - 1249 (2007/10/03)
The stabilisation of 3,4-pyridyne (1) by an alkoxy group adjacent to the ring nitrogen is reported. The regioselective lithiation of 2-ethoxy- (14), 2-methoxy- (18), 2-isopropoxy- (19) and 6-isopropoxy- (26) -3-chloropyridines with tertbutyllithium at low temperatures, followed by elimination of lithium chloride affords 2- and 6-alkoxy-3,4-pyridynes. These species are trapped m situ with furan in a Diels-Alder reaction to give 5-8 in 66-89% yield, and do not give products typical of polymerisation or nucleophilic addition to the 3,4-pyridyne intermediates. As a comparison treatment of 3-chloropyridine with furan and LDA gives only 19% of adduct (4). We also report the novel use of the isopropoxy (rather than methoxy) group in these systems, which can act as a heteroatomic electron donating group which inhibits a-lithiation by tert-butyllithium because of its increased steric bulk. The Royal Society of Chemistry 2000.
