Regio‐ and Stereoselective Tether‐Directed Remote Functionalization of C₆₀ with Derivatives of the Tröger Base

Abstract

Bringing two fascinating molecules together: Bismalonate derivatives of the Tröger base were used in the high‐yielding regio‐ and diastereoselective preparation of bisadducts of C60 with trans‐1, trans‐2, and trans‐4 addition patterns (e.g. see structure). Moreover, both enantiomers of the inherently chiral trans‐2 adduct were prepared from enantiomerically pure tethers.

Recent Developments in Synthetic Chemistry, Chiral Separations, and Applications of Tröger's Base Analogues

“…Based on the unambiguously determined absolute configuration of 1, absolute configurations of selected Trçgers base analogues were assigned by comparison of their CD spectra with those of 1 [19] [66]. However, in general, this method should be used with care.…”

Regio/diastereo-controls of the Bingel-type biscyclopropanation of [60]fullerene by using bismalonates with a Tröger base analogue-derived tether

“…Recently, Sergeyev and Diederich reported the application of Tröger base derivatives for the Bingel-type biscyclopropanation to obtain trans-1, trans-2, and trans-4 bisadducts with excellent regioselectivity. 7 We have independently attempted to show the utility of Tröger base derivatives for the tether-directed double Bingel reaction, especially focusing on the wide diversity of the synthetically available Tröger base derivatives with heteroaromatic rings. 8 From a synthetic viewpoint, the introduction of the derivatives with heteroaromatic rings has a significant advantage; some heteroaromatic rings can be easily and regioselectively modified with a hydroxycarbonyl, alkoxycarbonyl, and/or formyl group, which is readily converted to a hydroxymethyl group by simple reduction, in sharp contrast with the fact that available hydrocarbon aromatic amines with a hydroxymethyl group (or an equivalent functionality) are strictly limited, although such amines are indispensable for the construction of bismalonates tethered with a Tröger base derivative.…”

“…14 Although thus observed good regio-and diastereoselectivities were in good agreement with the results reported by Diederich et al, our reaction conditions would be rather suitable compared with their conditions from a practical viewpoint; the yields of the t 2 -1b and e-1b were highly improved without the deterioration of the regio/diastereoselectivities. 7 Taking into account the donor-acceptor interaction between C 60 and the tether core, further improvement in regio/diastereoselectivity might be expected by replacing the two benzene rings with heteroaromatic rings. Although various Tröger base derivatives are synthetically available, we decided to test thiophene and benzothiophene analogues, 3a and 4a, as the scaffolds of tethers in the biscyclopropanation reaction, because the relatively electron-rich five-membered ring and/or the lone pair of the sulfur atom might be work as electron-donating unit(s).…”

Synthesis and configuration determination of enantiopure 4,10-bis-ortho-substituted Tröger’s base derivatives

“…As the first chiral tertiary amine molecule, 1 had been resolved by Prelog and Wieland in 1944. 2 The unique structural features, including C2-symmetry, high rigidity, and a folded geometry with two aromatic ring planes almost perpendicular to each other, have made 1 and its analogues very intriguing for the application 3,4 as chiral solvating agents, 5,6 artificial receptors in molecular recognition, 7,8 DNA molecular probes, [9][10][11] , chiral tethers for the regio-and stereoselective tether-directed remote functionalization of fullerenes, [12][13][14] and chiral ligands for asymmetric catalysis.…”