Deformative Transition of the Menschutkin Reaction and Helical Atropisomers in a Congested Polyheterocyclic System was written by Chang, Yung-Yu;Ho, Tse-Lok;Chung, Wen-Sheng. And the article was included in Journal of Organic Chemistry in 2014.Application In Synthesis of 2-Isopropylpyridine This article mentions the following:
A 4,7-phenanthroline polycyclic 1A designed for probing the limits of the Menschutkin reaction was synthesized in a six-step sequence. The rotational barrier of the Ph ring nearby the N-Me group in rac-2A is â?8.1 kcal/mol from VT-NMR experiments, making them a new type of helical atropisomer. The methylation rate constants of 9 and 1A with MeI is 2.22 à 10-4 and 9.62 à 10-6 s-1 mol-1 L, resp.; thus, the formation rate of (P/M)-2A is one of the slowest rates ever reported for a Menschutkin reaction. The N-Me protons in (P/M)-2A exhibit a significant upfield shift (Îδ 1.0 ppm) in its 1H NMR, compared to those without a nearby Ph, indicating a strong CH-Ï interaction is involved. Conformational flexibility in dipyridylethene 9 is clearly shown by its complexation with BH3 to form helical atropisomers (P,P/M,M)-10. The pKa values of the conjugate acids of 1A and 9 in acetonitrile are 4.65 and 5.07, resp., which are much smaller compared to that of pyridine 14a (pKa = 12.33), implying that the basicity, nucleophilicity, and amine alkylation rates of 1A and 9 are markedly decreased by the severe steric hindrance of the flanking Ph rings in the polyheterocycles. In the experiment, the researchers used many compounds, for example, 2-Isopropylpyridine (cas: 644-98-4Application In Synthesis of 2-Isopropylpyridine).
2-Isopropylpyridine (cas: 644-98-4) belongs to pyridine derivatives. Pyridines are an important class of heterocycles and occur in polysubstituted forms in many naturally occurring biologically active compounds, drug molecules and chiral ligands. Many analogues of pyridine are known where N is replaced by other heteroatoms . Substitution of one C–H in pyridine with a second N gives rise to the diazine heterocycles (C4H4N2), with the names pyridazine, pyrimidine, and pyrazine.Application In Synthesis of 2-Isopropylpyridine