Preferential Photoreaction in a Porous Crystal, Metal–Macrocycle Framework: Pd^II-Mediated Olefin Migration over [2+2] Cycloaddition

Abstract

A nanosized confined space with well-defined functional surfaces has great potential to control the efficiency and selectivity of catalytic reactions. Herein we report that a 1,6-diene, which normally forms an intramolecular [2+2] cycloadduct under photoirradiation, preferentially undergoes a photoinduced olefin migration in a porous crystal, metal− macrocycle framework (MMF), and alternatively [2+2] cycloaddition is completely inhibited in the confined space. A plausible reaction mechanism for olefin migration triggered by the photoinduced dissociation of the Pd−Cl bond is suggested based on UV−vis diffuse reflectance spectroscopy, singlecrystal XRD, and MS-CASPT2 calculation. The substrate scope of the photoinduced olefin migration in MMF was also examined using substituted allylbenzene derivatives.

Controllable Isomerization of Alkenes by Dual Visible‐Light‐Cobalt Catalysis

“…Increasing the length of the carbon chain by one compared to allylbenzene has virtually no impact on the yield and the stereoselectivity (Table 2, entries [6][7][8][9][10]. All the allylbenzene derivatives underwent isomerization with good functional tolerance, generating the more stable trans-isomer in high yields ranging from 84 to 95 %( Table 2, entries 2-5).…”

“…Lanterna and Scaiano disclosed the photochemical isomerization of alkenes over one carbon using Pd-decorated TiO 2 as the photocatalyst, and very recently Shionoya established PdCl 2 centers on the inner surfaces of am etalmacrocycle framework (MMF) for photochemical alkene migration, but only benzyl-substituted alkenes were presented (Scheme 1c). [8] We report herein the combination of visible light catalysis with Co catalysis as aversatile protocol for the isomerization of alkenes.The activity of the generated Co hydride intermediates can be effectively controlled by ligands,t hus allowing the isomerization of alkenes with high regio-and stereo-selectivity (Scheme 1d).…”

Mechanistic Studies on Photoinduced Catalytic Olefin Migration Reactions at the Pd(II) Centers of a Porous Crystal, Metal‐Macrocycle Framework

“…This has been applied to site‐ or diastereo‐selective arrangement of guest molecules [27,28] and to size‐specific reactions catalyzed by an acid catalyst immobilized on the channel surface [29] . We also found a preferential photoreaction in MMF, where the photoinduced intramolecular cycloaddition of a 1,6‐diene was completely suppressed and instead olefin migration reaction took place by photoirradiation [30] . In the MMF pores, p ‐allylanisole ( 1 ) was also efficiently isomerized to internal olefin 2 by photoirradiation.…”

Nanoarchitectonics for Coordination Asymmetry and Related Chemistry

“…As shown in Figure 7, asymmetric architecture within porous metal-macrocycle framework provides environments for photoreaction controls. 62 Tashiro, Shionoya, and co-workers similarly prepared porous metal-macrocycle crystalline frameworks from trinuclear Pd II complexes of a macrocyclic hexamine. The formed porous crystals provided well-defined one-dimensional channels with several enantiomeric molecular binding sites.…”