Self-assembled orthoester cryptands: orthoester scope, post-functionalization, kinetic locking and tunable degradation kinetics

Abstract

Self-assembled orthoester cryptands offer appealing properties for applications in ion sensing and transport, such as convenient post-functionalization and tunable biodegradation.

Self‐Assembly of a Trithioorthoformate‐Capped Cyclophane and Its Endohedral Inclusion of a Methine Group

“…This unexpected structurei sh ypothesized to have formeda sar esult of haloform insertion during oxidation.Orthoesters and orthothioesters are functionalities seldom used in self-assembling supramolecular systemsd espite their relevance as acylating, alkylating, and formylating agents and as protecting groups in synthetic organic chemistry.R ecent work from vonD elius and co-workersf eatures the templated synthesis of dynamic orthoester cryptates, in which kinetic stabilization is induced via metal encapsulation. [1][2][3][4] Unique to this family is the addition of a single orthoformate group adjoining dissimilar ligandst og enerate as upramolecular heteroleptic self-assembly.Our presentwork focuses on metal-mediated dynamic covalent chemistry of disulfides and their capturev ia sulfur-extrusion. [5][6][7][8][9][10][11] In this study,w es how the surprising integration of at rithioorthoformate moiety using iodine oxidation of thiols to self-assemble an unexpected cyclophane cage featuring both at rithioorthoformate-cap and at ris-disulfideb ase (Scheme 1).…”

Self‐Assembly, Adaptive Response, and in,out‐Stereoisomerism of Large Orthoformate Cryptands

“…Following up on our preliminary studies on orthoformate o ‐(H in ) 2 ‐1.1.1 and o ‐(H out ) 2 ‐1.1.1 cryptands and their bridgehead inversion by dynamic covalent exchange, we aimed at exploring the potential in,out ‐isomerism of larger orthoformate 2.2.2 ‐cryptands. To this end, trimethoxy orthoformate and triethylene glycol (TEG) as ligand for cation binding were subjected to previously optimized conditions for orthoester exchange . By employing the large cesium template (CsBArF, see Figure S1 for K a determination), the desired cryptate [ Cs + ⊂ o ‐(H out ) 2 ‐2.2.2 ] was obtained in an isolated yield of 95 % (Figure a, I ).…”

“…Additionally, the average torsion angle (H−C−O−Cs + dihedrals) of 155° supports our previously described hypothesis that orthoformate cryptates tend to adopt a distorted geometry (Graph S9) compared to the corresponding orthoacetate cryptates, in which this angle is typically very close to 180°. In other words, orthoformate cryptands have smaller cavities than all other orthoester cryptands prepared to date, which needs to be considered, when predicting effective host‐guest pairs (Table S1).…”

Applications of alkyl orthoesters as valuable substrates in organic transformations, focusing on reaction media

“…Different kind of orthoesters also have many applications in several branches of science, such as polymers, [38][39][40][41][42][43] liquidcrystalline compounds, 44 biochemistry, [45][46][47][48][49] medicine [50][51][52][53][54][55][56] and medicinal organic chemistry, [57][58][59][60] inorganic chemistry, 61,62 organometallic chemistry, 63 dynamic covalent chemistry, 64 supramolecular chemistry, [65][66][67][68] and crystal structure analysis. 69 Orthoesters have also been used in the synthesis of natural products, e.g.…”