Chiral Polyaryl Cyclophanes

A series of propeller-shaped, C₃-symmetric cyclophanes have been synthesized by the macrocyclization of 1,3,5-trimercaptobenzene (12) with either a tris[o-(halomethyl)aryl]phosphine (e.g. 11) or a tris[o-(halomethyl)aryl]benzene (e.g. 24). Two phosphine-capped cyclophanes (5 and 6) were prepared in this way; they proved to be configurationally stable, and both were resolved into pure enantiomers by supercritical fluid chromatography on chiral supports. Compound 6, in particular, displayed a large specific rotation ([α]_D ≈ 800) and strong circular dichroism. The one triarylbenzene-capped cyclophane (9) that was made possessed a modest barrier to racemization (ΔG_rac^‡ = 15.7 kcal/mol). Computational studies of the trends in optical rotation for this class of compounds as well as the pathway for the racemization of 9 are also reported.

The synthesis of a series of propeller-shaped, C₃-symmetric cyclophanes is reported. Those with triarylphosphine caps are configurationally stable; they have been resolved and their chiroptical properties were measured. Those with triarylphenyl caps have a relatively low barrier to racemization.

from # All Medicine by Alexandros G. Sfakianakis via alkiviadis.1961 on Inoreader http://ift.tt/2tQYB2u