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Efficient Construction of Drug-like Bispirocyclic Scaffolds Via Organocatalytic Cycloadditions of α-Imino γ-Lactones and Alkylidene Pyrazolones
Published on: February 7, 2019
Syntheses, spectroscopic properties and stereochemistry of bis-C-pivot macrocycles with two dialkyl phosphonate
Selen Bilge1, Zeynel Kılıç, David B Davies
1Department of Chemistry, Ankara University, 06100 Tandoğan-Ankara, Turkey. sbilge@science.ankara.edu.tr
Abstract:
Bis-C-pivot macrocycles containing dimethyl (1a, 2a) or diethyl phosphonate (1b, 2b) groups have been prepared by adding dimethyl or diethyl phosphite to two -CH=N bonds in corresponding dibenzo-bis-imino crown ethers (1 and 2). Bis-C-pivot macrocycles possess two equivalent stereogenic centres giving rise to diastereoisomers (meso and racemate). The structures were characterized by elemental analysis, FTIR, MS, TGA, DSC and NMR measurements. (1)H, (13)C and (31)P NMR assignments were made for the isolated meso form of compounds 2a and 2b and for the meso and racemic forms of compounds 1a and 1b by analysis of chemical shifts, signal intensities and splitting patterns and the DEPT and 2D HETCOR NMR techniques. Thermal analysis and (1)H NMR showed that the crystallised form of compound 1a contained an equimolar amount of water of crystallisation.
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