Synthesis of γ-lactols, γ-lactones and 1,4-monoprotected succinaldehydes under moderately concentrated sunlight

Sulfur‐Center‐Involved Photocatalyzed Reactions

“…If 1,3‐dioxane 9 was used, only Michael addition happened [Eq. (4)] . Ten‐gram‐scale reactions could be completed within 10 to 15 h in a relatively simple flow system, with yields of 31 to 83 % when the reactions were exposed to sunlight in a solar concentrator.…”

“…(4)]. [13] Te n-gram-scale reactions could be completed within 10 to 15 hi narelatively simple flow system, with yields of 31 to 83 %w hen the reactions were exposed to sunlight in as olar concentrator.A lthough the efficiency was now high enough, this system demonstratedt he potentialo f transforming solare nergy to chemical energyo nl arge scales. The proposed mechanism is shown in Scheme 1: BPSS 3 is activated by solarl ight and absorbs ah ydrogen atom from the a positiono ft he oxygen atom.…”

“…In 2016, Jiang et al achieved ac hemidivergent strategy for the controllable synthesis of indole derivatives with DPZ as a PC, in which different additives playedi mportant roles in the (13) and (14)]. [23] Ap ossible mechanism is presented in Scheme 9: the excited DPZ* PC is quenched by THCs or THIQs, which generates DPZ À C and amino radicalc ation A.D PZ À C is oxidized by oxygen to form O 2 À C,w hich abstracts ah ydrogen atom from A to produce iminiums B.I ntermediate C,o btained from the nucleophilic addition of Lewis base b-isocupreidine (b-ICD) 70 to electron-deficient alkenes, attacks B through aM annich-type reaction to give 66 and 67 via intermediate E.I norganic salt NaBArF 69,w hich is known to have good affinity for carboxylate and carbonyl oxygen atoms, is likely involved in the activa- tion of the acrolein carbonyl group to benefitt he addition of b-ICD, which stabilizes iminiums B and bridges nucleophilic intermediate C and iminiums B into the transition states D through multisite coordination.…”

C1 Oxidation/C2 Reduction Isomerization of Unprotected Aldoses Induced by Light/Ketone

“…[9] Unlike in the case of ionic reactions,r adical reactions are hardly affected by water as as olvent. We envisaged that aw ater-soluble benzophenone derivative,f or example,b enzophenone sodium sulfonate (BPSS) [10] would operate upon unprotected sugars in water. Thus,f ree dglucose (1a)i nw ater was initially irradiated with UV light (365 nm) at ambient temperature in the presence of BPSS (50 mol %), and no reaction occurred.…”

Design Consideration of Continuous-Flow Photoreactors

“…14 Notably, loop facilities have been intensively employed when concentrated sunlight was used as the light source. 15,16 On contrast, when moving to flow photochemical technologies, the reduced size of the reaction channels allows for an efficient light absorption by the substrate, along with a more precise control of reaction time, temperature, pressure and mixing. Furthermore, since the product is continuously removed from the irradiation window, degradation resulting from over-exposition of the desired material is avoided.…”