An efficient transition-metal-free amination of benzoxazoles has been developed. With catalytic amounts of tetrabutylammoniumiodide (TBAI), aqueous solutions of H(2)O(2) or TBHP as co-oxidant and under mild reaction conditions, highly desirable 2-aminobenzoxazoles were isolated in excellent yields of up to 93%. First mechanistic experiments indicate the in situ iodination of the secondary amine as the putative mode of activation.

An oxidative and acid-free method for the nitration of N-aryl sulfonamides has been developed using a combination of sodium nitrite as cheap and easy to handle NO2-source and the hypervalent iodine reagent PIFA as stoichiometric oxidant. Under very mild reaction conditions, the desired mononitrated aryl sulfonamides were isolated in up to 87% yield. This is the first example of an iodane-mediated oxidative nitration.

The first direct alkynylation of 2-vinylphenols was developed. The rationally optimized hypervalent iodine reagent TIPS-EBX* in combination with [(Cp*RhCl2)2] as a C-H-activating transition metal catalyst enables the construction of a variety of highly substituted 1,3-enynes in high yields of up to 98%. This novel C-H activation method shows excellent chemoselectivity and exclusive (Z)-stereoselectivity, and it is also remarkably mild and tolerates a variety of functional groups. Furthermore, synthetic modifications of the resulting 1,3-enynes were demonstrated. To our knowledge, this is the first example for an OH-directed C-H alkynylation with hypervalent iodine reagents.

An efficient iodine-catalyzed synthesis of highly substituted oxazoles is presented. Starting from readily available aryl methyl ketones, β-keto esters, or styrenes, in combination with α-amino acids as amine-containing coupling partners, the corresponding 2-alkyl-5-aryl- substituted oxazoles were obtained in up to 80% yield via a decarboxylative domino reaction.

An iodocyclization reaction of o-alkynylphenyl carboxaldehydes is reported that is truly catalytic with respect to the electrophilic iodine source. With a combination of tetrabutylammonium iodide (TBAI), Oxone as non-nucleophilic and easy to handle co-oxidant, and fluorinated protic solvents, highly substituted 1-naphthalenones could be prepared in high yields of up to 91%.

Supporting Information I. General Methods 1 H NMR spectra were recorded on an Avance 400 MHz instrument in deuterated chloroform CDCl 3. Chemical shifts (δ) are given in parts per million (ppm). 1 H NMR spectra were referenced to the residual hydrogen signal in CDCl 3 at δ = 7.26 ppm or to residual hydrogen singulet signal at δ = 4.84 ppm when measured in methanol-d 4. 13 C NMR spectra were recorded on 100 MHz and were fully decoupled by broad band decoupling. 13 C spectra were referenced to the CDCl 3 triplet signal at δ = 77.0 ppm or to septet signal at δ = 49.05 ppm in methanol-d 4. The following abbreviations were used to describe splitting patterns: br = broad, s = singlet, d = doublet, t = triplet, q = quartet, dt = doublet of triplet, m = multiplet. Coupling constants J are given in Hz. Mass spectra were recorded on a Finnigan MAT95 by using EI or FAB method. HRMS was measured on a APEX II Bruker DALTONICS ESI FT-ICR-MS. Thin layer chromatography was performed on fluorescence indicator marked precoated silca gel 60 plates (Macherey-Nagel, ALUGRAM Xtra SIL G/UV 254) and visualization was achieved by UV light (254 nm). Gas chromatography was measured on a Hewlett Packard 5890 (chiral column: 977 TBDMS-diacetyl-beta-CD). Flash chromatography was performed on silica gel (0.040-0.063 mm). Unless otherwise stated all reactions were carried out under air. For air or moisture sensitive reactions standard Schlenk-techniques were applied under an argon atmosphere. Schlenk-glassware was heated in vacuo and flushed with argon several times before they were used. Reagents and solvents were added by syringe/septum techniques. IR spectra were recorded on JASCO FT/IR-4100. A selection of S2 signals is given in reciprocal centimeters (cm-1). Optical rotary power was recorded on a JASCO P-1020 in MeOH with a concentration of C=1. Solvents and reagents For all conversions HPLC grade acetonitrile was used. Solvents for flash chromatography (hexane, ethyl acetate, dichloromethane) were distilled before use. Morpholine was distilled before use. Benzoxazole derivatives were synthesized and purified according to a literature procedure from their ortho-aminophenol derivatives (S. H. Cho, J. Y.

Wirb erichten über die Entwicklung der ersten direkten Alkinylierung von 2-Vinylphenolen. Das optimierte hypervalente Iodreagens TIPS-EBX* ermçglicht zusammen mit [(Cp*RhCl 2 ) 2 ]a ls Übergangsmetallkatalysator die Konstruktion einer Vielzahl von hochsubstituierten 1,3-Eninen in Ausbeuten von bis zu 98 %. Diese neue C-H-aktivierende Methode zeichnet sich durch eine exzellente Chemoselektivität und reine (Z)-Stereoselektivität aus,i st dabei besonders mild und toleriert viele funktionelle Gruppen. Des Weiteren wurden Modifikationen der so erhaltenen 1,3-Enine untersucht. Unseres Wissens ist diese Reaktion das erste Beispiel einer OHdirigierten C-H-Alkinylierung mit hypervalenten Iodreagentien.Hintergrundinformationen zu diesem Beitrag sind im WWW unter http://dx.

Two complimentary methods for the TBAI‐catalyzed oxidative amination of benzoxazoles are developed applying H2O2 or tBuOOH as oxidants.