Supramolecular Control of Photocycloadditions in Solution: In Situ Stereoselective Synthesis and Release of Cyclobutanes

Abstract

A new class of supramolecular metallacycles capable of undergoing photochemical reactions and in situ release of cyclobutanes in solution is described. The molecular metallacycles were generated through coordination‐driven self‐assembly of dinuclear metal‐carbene complexes as organometallic clips with olefin‐functionalized bridging ligands. Photolysis of these molecular metallacycles in situ led to structural interconversion and release of the formed cyclobutane products with quantitative conversion. Further modifications of the obtained cyclobutanes provided a series of new species containing the cyclobutane skeleton.

Metal‐Carbene‐Templated Photochemistry in Solution: A Universal Route towards Cyclobutane Derivatives

“…Colorless crystals of complex [Ag 2 ( 4 )](PF 6 ) 2 were obtained by slow diffusion of dichloromethane into the saturated acetonitrile/DMSO (1: 1) solution of the compound at ambient temperature. The bond parameters (Ag—C NHC bond lengths 2.082(14)— 2.147(13) Å and bond angles C NHC ‐Ag‐C NHC 178.2(5)°) found in complex [Ag 2 ( 4 )](PF 6 ) 2 fall in the range previously observed for related [Ag(NHC) 2 ] complexes …”

“…First, we focused on the 1,2,4‐triazole‐based compounds. ( E )‐1,2‐Bis(4‐(1 H ‐1,2,4‐triazol‐1‐yl)phenyl)ethene was prepared by following a literature reported procedure . The subsequent alkylation of ( E )‐1,2‐bis(4‐(1 H ‐1,2,4‐triazol‐1‐yl)phenyl)ethene with selected alkyl halides afforded bis(1,2,4‐triazolium)‐substituted stilbene derivatives H 2 ‐ 1 (PF 6 ) 2 and H 2 ‐ 2 (BF 4 ) 2 in 76% and 89% yields (see Supporting Information (SI), Scheme S1).…”

“…All other chemical reagents were commercially available and used directly without further purification. ( E )‐1,2‐Bis(4‐(1 H ‐1,2,4‐triazol‐1‐yl)phenyl)ethene, ( E )‐1,2‐ bis(4‐ethynylphenyl)ethane and ( E )‐4,4'‐(ethene‐1,2‐diyl)dianiline were synthesized according to reported procedures. NMR spectra were recorded on Bruker AVANCE I 400 spectrometers.…”

Supramolecular Control of Photocycloadditions in Solution: In Situ Stereoselective Synthesis and Release of Cyclobutanes

“…Twoviews of the crystallographically derived molecular structure of the tetracationo f3a (hydrogen atoms omitted for clarity and only the first atom of each N-n Bu substituenti sdepicted). [25] Thermal ellipsoids shown at 30 %probability. Figure 5.…”

Construction of Metallacycle‐Linked Heteroarm Star Polymers via Orthogonal Post‐Assembly Polymerization and Their Intriguing Self‐Assembly into Large‐Area and Regular Nanocubes†

“…According to the general principles of coordination‐driven self‐assembly, [ 16‐28 ] a new 120° dipyridyl donor 1 containing hydroxy group (Figure S1) for the ring‐opening polymerization and 120° di‐Pt(II) acceptor 2 decorated with chain transfer agent (CTA) were selected for the construction of a discrete hexagonal metallacycle. [ 29‐36 ] As shown in Scheme 1, the complexation reaction was conducted by mixing an equimolar mixture of 1 and 2 in a solution of acetone and water ( V : V = 5 : 1) at 50 °C for 5 h. From the 1 H NMR analysis of the resultant complex, the protons of the pyridine rings exhibited obvious downfield shifts ( α ‐H Py , δ 0.40; β ‐H Py , δ 0.42) as compared to the uncoordinated ligands, which are associated with the loss of electron density upon coordination by the pyridine‐N atom with the platinum metal centers (Figure 1).…”