Photochemical Alkene Isomerization for the Synthesis of Polysubstituted Furans and Pyrroles under Neutral Conditions

Abstract

Ap hotochemical approacht op olysubstituted heterocycles using UV-induced alkene isomerization is described.T he method allows for the synthesis of disubstituted furans and pyrroles under mild and neutral conditions and also providesa ccesst oac lass of trisubstituted furans pertinent to natural-product synthesis. The method has broad functional-group tolerance and many richly decorated heterocycles have been prepared incorporating functional groups that are unstable under Brønsted and Lewis acidic conditions. Scheme1.Importance of aromatic heterocyclic compounds andstrategies for their synthesis from acyclic precursors.[a] Dr.

A Heck reaction/photochemical alkene isomerization sequence to prepare functionalized quinolines

“…We then turned to the isomerization of the Heck reaction products, which we hoped would furnish the target quinolines. The UV-Vis absorption spectra of 3aa demonstrated that, as before, [10] the enone intermediates absorbed in the 300-400 nm range and should be able to absorb at the wavelength provided by a commercially available 365 nm Pen-Ray source (see Supporting Information for UV-Vis spectra). [20] We were delighted to find that all of the Heck reaction products could indeed be isomerized and cyclized to the corresponding quinolines in high yields at 0 o C (Scheme 5).…”

“…[9] We recently reported an alkene metathesis/photochemical isomerization approach for the rapid synthesis of functionalized furans and pyrroles (Scheme 1, bottom). [10] A number of acid-sensitive functionalities could be incorporated into the target using the mild photochemical conditions and we wondered whether a similar strategy could also be applied to quinoline synthesis. [11] Our plan was to perform a Heck reaction [12] between readily available ortho-bromoanilines (in contrast to the less common ortho-iodoanilines which are conventionally used) and enones to access β-aryl-α,β-unsaturated ketones.…”

Heteroleptic Copper-Based Complexes for Energy-Transfer Processes: E → Z Isomerization and Tandem Photocatalytic Sequences

“…15 Weaver and co-workers have studied the use of Ir(ppy) 3 for the isomerization of allylic amines, 16 while Gilmour and co-workers have exploited (−)-riboflavin for a host of isomerization processes. 17 The value of isomerization can be illustrated by tandem processes utilizing the Z-isomer, which consist of isomerization followed by C−C cross-coupling 18,19 C−O cross-coupling, 20 selective reduction, 21 condensation/cyclization, 22 and photochemical [2 + 2] cycloaddition. 23 Herein, we report on the design of a heteroleptic copper-based photosensitizer for E ↔ Z isomerization via energy transfer.…”

“…The value of isomerization can be illustrated by tandem processes utilizing the Z -isomer, which consist of isomerization followed by C–C cross-coupling , C–O cross-coupling, selective reduction, condensation/cyclization, and photochemical [2 + 2] cycloaddition . Herein, we report on the design of a heteroleptic copper-based photosensitizer for E ↔ Z isomerization via energy transfer.…”

DFT Study on the Gold(I)‐Catalyzed Dehydrogenative Heterocyclization of 2‐(1‐Alkynyl)‐2‐alken‐1‐ones to form 2,3‐Furan‐Fused Carbocycles: Effects of Additives C5H5NO vs. PhNO

“…Furans can not only be used as key structural units in a number of biological active natural products, pharmaceuticals, and agrochemicals, [1][2][3][4][5] but can also act as important precursors in the synthesis of acyclic, carbocyclic, and heterocyclic compounds. [6][7][8][9] Owing to the reasons above, the substituted furans have played a crucial role in catalytic synthesis reactions in recent decades.…”