Many-Membered Carbon Rings. Xxi. Resolution of [10]paracyclophane-12-Carboxylic Acid

Hydrogen‐Bond Control in Axially Chiral Styrenes: Selective Synthesis of Enantiomerically Pure C2‐Symmetric Paracyclophanes

“…Scheme 1 illustrates the narrow borderline between resolvable and nonresolvable structures: The [12]cyclophane II with two substituents is resolvable, whereas I with a single substituent is not resolvable. [7] Herein, we propose a fairly general strategy for the synthesis of enantiomerically pure cyclophanes.The strategic basis for our approach is a symmetry consideration illustrated by a "plate-and-stick model" (Figure 1): The connection of two identical sticks to the upper side of a C 2h -symmetric plate A, which represents an aromatic platform, would give the C 2 -symmetric "precyclophane" B. [7] Herein, we propose a fairly general strategy for the synthesis of enantiomerically pure cyclophanes.…”

“…To avoid flipping of the ansa chain, and hence racemization, two general strategies are available: 1) the use of a shorter ansa chain, [3] and 2) the installment of many and/or large substituents on the aromatic ring. [7] Herein, we propose a fairly general strategy for the synthesis of enantiomerically pure cyclophanes. [4] Even when such guidelines are followed, another challenge is the enantioselective synthesis of these structures; [5, 6] tedious optical resolution has been the approach traditionally employed.…”

“…[4] Even when such guidelines are followed, another challenge is the enantioselective synthesis of these structures; [5, 6] tedious optical resolution has been the approach traditionally employed. [7] Herein, we propose a fairly general strategy for the synthesis of enantiomerically pure cyclophanes.The strategic basis for our approach is a symmetry consideration illustrated by a "plate-and-stick model" (Figure 1): The connection of two identical sticks to the upper side of a C 2h -symmetric plate A, which represents an aromatic platform, would give the C 2 -symmetric "precyclophane" B. To complete an enantioselective route to the C 2 -…”

“…[4] Even when such guidelines are followed, another challenge is the enantioselective synthesis of these structures; [5, 6] tedious optical resolution has been the approach traditionally employed. [7] Herein, we propose a fairly general strategy for the synthesis of enantiomerically pure cyclophanes.…”

“…The C 2 symmetry also facilitates the synthesis of the key compound IV, which can be assembled from an aryl diboronic acid V and two equivalents of vinyl iodide VI. [7] Scheme 1. Stereochemical features of paracyclophanes.…”