Fig. 2: Synthesis and characteristics of macrocycle OC-4.
From: Controlled interconversion of macrocyclic atropisomers via defined intermediates
a Synthesis of macrocycle OC-4. Reaction conditions: (I) 1 (1 equiv.), 3 (1 equiv.), CsF (25 equiv.) and Pd(dppf)2Cl2• CH2Cl2 (0.20 equiv.) in toluene, 373 K, 12 h, C2v-OC-4, trace, C4v-OC-4, 31%; (ii) 1 (1 equiv.), 3 (1 equiv.), CsF (25 equiv.) and Pd(dppf)2Cl2• CH2Cl2 (0.20 equiv.) in acetonitrile, 333 K, 48 h, C2v-OC-4, 7%, C4v-OC-4, 8%. b Structures and conformational studies of macrocycle OC-4. (b1) Heating induced quantitative conformational change from C2v- to C4v-OC-4 in solid state; (b2) and (b3), or (b4) and (b5), top and side views of C2v- or C4v-OC-4 with a stick form in the single crystal of [C2v-OC-4•5CYH] or [C4v-OC-4•3CYH], respectively. The insert is the thin layer chromatography (TLC) analysis on silica gel plates (eluent: petroleum ether: ethyl acetate = 3:1, v/v) of C2v-, C4v-OC-4, and the conversion at 573 K. c1–c2 1H NMR spectra of 5.00 mM C4v-OC-4 (c1) and C2v-OC-4 (c2) recorded in TCE-d2 at 298 K (500 MHz). d Expanded view of the temperature-dependent 1H NMR spectra of C2v-OC-4 (5.00 mM) in TCE-d2 (500 MHz).
