Functionally diverse nucleophilic trapping of iminium intermediates generated utilizing visible light.

Our previous studies into visible-light-mediated aza-Henry reactions demonstrated that molecular oxygen played a vital role in catalyst turnover as well as the production of base to facilitate the nucleophilic addition of nitroalkanes. Herein, improved conditions for the generation of iminium ions from tetrahydroisoquinolines that allow for versatile nucleophilic trapping are reported. The new conditions provide access to a diverse range of functionality under mild, anaerobic reaction conditions as well as mechanistic insights into the photoredox cycle.

[1]  W. Xiao,et al.  Visible light-induced intramolecular cyclization reactions of diamines: a new strategy to construct tetrahydroimidazoles. , 2011, Chemical communications.

[2]  Vincenzo Balzani,et al.  Ru(II) polypyridine complexes: photophysics, photochemistry, eletrochemistry, and chemiluminescence , 1988 .

[3]  Chao‐Jun Li,et al.  CuBr-catalyzed direct indolation of tetrahydroisoquinolines via cross-dehydrogenative coupling between sp3 C-H and sp2 C-H bonds. , 2005, Journal of the American Chemical Society.

[4]  C. Yeung,et al.  Catalytic dehydrogenative cross-coupling: forming carbon-carbon bonds by oxidizing two carbon-hydrogen bonds. , 2011, Chemical reviews.

[5]  V. Balzani.  Electron transfer in chemistry , 2001 .

[6]  M. A. Ischay,et al.  Visible light photocatalysis as a greener approach to photochemical synthesis. , 2010, Nature chemistry.

[7]  N. Shankaraiah,et al.  Short synthesis of noscapine, bicuculline, egenine, capnoidine, and corytensine alkaloids through the addition of 1-siloxy-isobenzofurans to imines , 2010 .

[8]  Kuppuswamy Kalyanasundaram,et al.  Photophysics, photochemistry and solar energy conversion with tris(bipyridyl)ruthenium(II) and its analogues , 1982 .

[9]  Jennifer J. Becker,et al.  Investigating the rate of photoreductive glucosyl radical generation. , 2011, Organic letters.

[10]  Chao‐Jun Li,et al.  CuBr-catalyzed efficient alkynylation of sp3 C-H bonds adjacent to a nitrogen atom. , 2004, Journal of the American Chemical Society.

[11]  Wei Xu,et al.  Substituent effects on amine cation radical acidity. Regiocontrol of .beta.-(aminoethyl)cyclohexenone photocyclizations , 1991 .

[12]  Carlos Vila,et al.  Dual catalysis: combining photoredox and Lewis base catalysis for direct Mannich reactions. , 2011, Chemical communications.

[13]  Corey R J Stephenson,et al.  Visible light photoredox catalysis: applications in organic synthesis. , 2011, Chemical Society reviews.

[14]  C. Farés,et al.  Mechanistic studies on a Cu-catalyzed aerobic oxidative coupling reaction with N-phenyl tetrahydroisoquinoline: structure of intermediates and the role of methanol as a solvent. , 2011, Journal of the American Chemical Society.

[15]  A. Nicholas,et al.  Thermochemical parameters for organic radicals and radical ions. Part 1. The estimation of the pKa of radical cations based on thermochemical calculations , 1982 .

[16]  F. Teplý.  Photoredox catalysis by [Ru(bpy)3]2+ to trigger transformations of organic molecules. Organic synthesis using visible-light photocatalysis and its 20th century roots , 2011 .

[17]  S. Geib,et al.  How do analogous alpha-chloroenamides and alpha-iodoenamides give different product distributions in 5-endo radical cyclizations? , 2008, Journal of the American Chemical Society.

[18]  M. Akita,et al.  Photoinduced Oxyamination of Enamines and Aldehydes with TEMPO Catalyzed by [Ru(bpy)3]2+ , 2009 .

[19]  C. Stephenson,et al.  Visible-light photoredox catalysis: aza-Henry reactions via C-H functionalization. , 2010, Journal of the American Chemical Society.

[20]  Jagan M. R. Narayanam,et al.  Visible-light-mediated conversion of alcohols to halides. , 2011, Nature chemistry.

[21]  Xue-Yuan Liu,et al.  Selective functionalization of sp(3) C-H bonds adjacent to nitrogen using (diacetoxyiodo)benzene (DIB). , 2009, The Journal of organic chemistry.

[22]  Jennifer J. Becker,et al.  Intermolecular addition of glycosyl halides to alkenes mediated by visible light. , 2010, Angewandte Chemie.

[23]  Chao‐Jun Li,et al.  Copper catalyzed oxidative alkylation of sp3 C–H bond adjacent to a nitrogen atom using molecular oxygen in water , 2007 .

[24]  P. Rahimi-Moghaddam,et al.  The anti-cancer activity of noscapine: a review. , 2009, Recent patents on anti-cancer drug discovery.

[25]  Magnus Rueping,et al.  Photoredox catalyzed C-P bond forming reactions-visible light mediated oxidative phosphonylations of amines. , 2011, Chemical communications.

[26]  I. Gould,et al.  α-C−H Bond Dissociation Energies of Some Tertiary Amines , 1999 .

[27]  Chao‐Jun Li.  The development of catalytic nucleophilic additions of terminal alkynes in water. , 2010, Accounts of chemical research.

[28]  T. Bach,et al.  Photochemical reactions as key steps in natural product synthesis. , 2011, Angewandte Chemie.

[29]  S. Nelsen,et al.  On the deprotonation of trialkylamine cation radicals by amines , 1986 .

[30]  Chao‐Jun Li.  Cross-dehydrogenative coupling (CDC): exploring C-C bond formations beyond functional group transformations. , 2009, Accounts of chemical research.

[31]  Durga Prasad Hari,et al.  Eosin Y catalyzed visible light oxidative C-C and C-P bond formation. , 2011, Organic letters.

[32]  Visible-light photoredox catalysis: dehalogenation of vicinal dibromo-, α-halo-, and α,α-dibromocarbonyl compounds. , 2011, The Journal of organic chemistry.

[33]  M. A. Ischay,et al.  Efficient visible light photocatalysis of [2+2] enone cycloadditions. , 2008, Journal of the American Chemical Society.

[34]  M. Klussmann,et al.  Oxidative coupling of amines and ketones by combined vanadium- and organocatalysis. , 2009, Chemical communications.

[35]  Chao‐Jun Li,et al.  Highly efficient copper-catalyzed nitro-Mannich type reaction: cross-dehydrogenative-coupling between sp3 C-H bond and sp3 C-H bond. , 2005, Journal of the American Chemical Society.

[36]  Megan A. Cismesia,et al.  Visible Light Photocatalysis of Radical Anion Hetero-Diels-Alder Cycloadditions. , 2011, Tetrahedron.

[37]  D. MacMillan,et al.  Photoredox catalysis: a mild, operationally simple approach to the synthesis of α-trifluoromethyl carbonyl compounds. , 2011, Angewandte Chemie.

[38]  W. Xiao,et al.  Visible-light-induced oxidation/[3+2] cycloaddition/oxidative aromatization sequence: a photocatalytic strategy to construct pyrrolo[2,1-a]isoquinolines. , 2011, Angewandte Chemie.

[39]  Joseph W Tucker,et al.  Electron-transfer photoredox catalysis: development of a tin-free reductive dehalogenation reaction. , 2009, Journal of the American Chemical Society.

[40]  Laura Furst,et al.  Total synthesis of (+)-gliocladin C enabled by visible-light photoredox catalysis. , 2011, Angewandte Chemie.

[41]  S. Murahashi,et al.  Ruthenium catalyzed biomimetic oxidation in organic synthesis inspired by cytochrome P-450. , 2008, Chemical Society reviews.

[42]  Chao‐Jun Li,et al.  Aerobic and electrochemical oxidative cross-dehydrogenative-coupling (CDC) reaction in an imidazolium-based ionic liquid. , 2010, Chemistry.

[43]  H. Takaya,et al.  Low-valent ruthenium and iridium hydride complexes as alternatives to Lewis acid and base catalysts. , 2000, Accounts of chemical research.

[44]  J. Dannenberg,et al.  Oxidation potentials of α-aminoalkyl radicals: bond dissociation energies for related radical cations , 1986 .

[45]  David A. Nicewicz,et al.  Merging Photoredox Catalysis with Organocatalysis: The Direct Asymmetric Alkylation of Aldehydes , 2008, Science.

[46]  D. Curran,et al.  Tandem radical approach to linear condensed cyclopentanoids. Total synthesis of (.+-.)-hirsutene , 1985 .

[47]  T. Nakae,et al.  Ruthenium-catalyzed oxidative cyanation of tertiary amines with molecular oxygen or hydrogen peroxide and sodium cyanide: sp3 C-H bond activation and carbon-carbon bond formation. , 2008, Journal of the American Chemical Society.