It's the power of light! A visible‐light‐mediated intermolecular [3+2] cycloaddition of mono‐ and bicyclic cyclopropylamines with olefins catalyzed by [Ru(bpz)3](PF6)2⋅2 H2O has been developed to furnish aminocyclopentane derivatives in good yields (see scheme, bpz=2,2′‐bipyrazine). Saturated 5,5‐ and 6,5‐fused heterocycles are obtained in synthetically useful yields and diastereoselectivity.

Indoles: A joint effort of light and air We have developed a mild aerobic oxidation protocol using visible light photocatalysis to synthesize structurally diverse N-arylindoles. The procedure employs 4 mol% [Ru(bpz)3](PF6)2, 18W LED light, and is performed open to the atmosphere. Readily prepared o-stryryl anilines are converted to a variety of indoles via a cascade sequence composed of oxidation of anilines, C-N bond formation, and aromatization. A 1,2-carbon shift can be also incorporated into this cascade event to further extend the substrate scope of the method. bpz = 2, 2′-Bipyrazine

SummaryIntermolecular [3 + 2] annulation of cyclopropylanilines with alkynes is realized using visible light photoredox catalysis, yielding a variety of cyclic allylic amines in fair to good yields. This method exhibits significant group tolerance particularly with heterocycles. It can also be used to prepare complex heterocycles such as fused indolines.

An efficient and highly selective approach for intermolecular arylthiocyanation/arylselenocyanation of alkenes has been reported under mild conditions. Using diazonium salts as the arylating agent and ammonium thiocyanate as the thiocyanate source, chemoselective difunctionalization of alkenes has been done under irradiation of visible light. Both styrenes and acrylates work well to deliver various aryl-substituted alkylthiocyanates in good to excellent yields. In addition, hitherto unknown β-aryl alkylselenocyanates were also synthesized using the developed protocol with potassium selenocyanate.

Solar energy is clean, abundant, and more importantly, renewable. As such, any reaction that efficiently harvests and converts solar energy into chemical energy is more important than ever as the world turns to its scientists to meet the challenge of environmental sustainability. Visible light (390-750 nm) accounts for 43% of the overall solar spectrum. However, many organic molecules are unable to absorb visible light efficiently, thereby limiting the use of visible light in organic synthesis. A possible solution to this problem involves the use of visible-light photoredox catalysts such as ruthenium [1] or iridium [2] polypyridyl complexes to channel energy from visible light into organic molecules. The groups of MacMillan, [3] Yoon, [4] Stephenson, [5] Akita, [6] and others [7] have recently published seminal works on visible-light-promoted C-C bond-formation reactions catalyzed by these complexes. Amines are often used as a sacrificial electron donor to reduce the photoexcited Ru II and Ir III complexes to Ru I and Ir II complexes. [8] Recently, amines have been also explored as a substrate in these processes. [9] We were intrigued by the potential of using amines as both the sacrificial donor and the substrate, thus making the process more atom economical.We envisioned a class of amines that are capable of initializing a downstream irreversible reaction upon oxidation by the photoexcited Ru II or Ir III complexes. Cyclopropylamines have been shown to undergo irreversible opening of the cyclopropyl ring upon their oxidation to the nitrogen radical cations. Based on this mode of action, cyclopropylamines have been used to probe amine oxidation in biological systems. [10] Cyclopropylamines have seen limited use in organic synthesis to date. [11] All these applications focus on intramolecular reactions, except the formation of the endoperoxides. [11a] Furthermore, the generation of nitrogen radical cations requires UV light with a photosensitizer or a strong oxidant (e.g., ceric ammonium nitrate), thus limiting the substrate scope and/or the type of the products being formed. Since visible-light photocatalysis has been shown to be a mild and chemoselective method to oxidize amines, we envisioned that new transformations of cyclopropylamines catalyzed by a Ru II or Ir III polypyridyl complex could be developed (Scheme 1). Herein we report an intermolecular [3+2] cycloaddition of olefins with monoand bicyclic cyclopropylanilines under visible light photocatalysis. ** We thank the University of Arkansas, the Arkansas Bioscience Institute, and the NIH NCRR COBRE grant (P30 RR031154) for generous support of this research. R.S.S thanks the Division of Organic Chemistry of the ACS for a SURF award. We also thank Prof. Bill Durham for insightful discussions on photochemistry and Prof. Jim Hinton for obtaining NOESY spectra.