Enantioselective Construction of Modular and Asymmetric Baskets

Abstract

The precise positioning of functional groups about the inner space of abiotic hosts is ac hallenging task and of interest for developing more effective receptors and catalysts akin to those found in nature.T oa ddress it, we herein report as ynthetic methodology for preparing basket-like cavitands comprised of three different aromatics as side arms with orthogonal esters at the rim for further functionalization. First, enantioenriched A (borochloronorbornene), B (iodobromonorbornene), and C (boronorbornene) building blocks were obtained by stereoselective syntheses.S econd, consecutive Ato-B and then AB-to-C Suzuki-Miyaura (SM) couplings were optimizedt og ive enantioenriched ABC cavitand as the principal product. The robust synthetic protocol allowed us to prepare (a) an enantioenriched basket with three benzene sides and each holding either tBu, Et, or Me esters,( b) both enantiomers of as o-called "spiral staircase" basket with benzene, naphthalene,a nd anthracene groups surrounding the inner space,and (c) aphoto-responsive basket bearing one anthracene and two benzene arms.

Closed Aromatic Tubes—Capsularenes

“…To obtain longer capsularenes holding naphthalimide 8 and anthraceneimide 9 sides (Figure 6A), we prepared tris-acetal baskets 6 and 7 using already established procedures. [46] After 6 or 7 were each dissolved in CH 2 Cl 2 and subjected to an excess of TFA, there followed the exclusive formation of 8 and 9, respectively (Figure S16/S19). Importantly, a set of 1 H NMR resonances from tris-acetal baskets 6 or 7 under-…”

Closed Aromatic Tubes—Capsularenes

“…To obtain longer capsularenes holding naphthalimide 8 and anthraceneimide 9 sides (Figure 6A), we prepared tris-acetal baskets 6 and 7 using already established procedures. [46] After 6 or 7 were each dissolved in CH 2 Cl 2 and subjected to an excess of TFA, there followed the exclusive formation of 8 and 9, respectively (Figure S16/S19). Importantly, a set of 1 H NMR resonances from tris-acetal baskets 6 or 7 under- goes similar magnetic perturbations upon the formation of 8 and 9 (Figure 6A).…”