An efficient asymmetric synthesis of D-α-(uracil-5-yl)glycine derivatives using an enzymatic dynamic kinetic resolution of D,L-hydantoin intermediates with an immobilized D-hydantoinase (D-Hyd-1) is described. In addition, mild conditions for a racemization-free solid-phase peptide synthesis (SPPS) using the Fmoc strategy have been found.

Wir berichten über die Entwicklung der ersten direkten Alkinylierung von 2-Vinylphenolen. Das optimierte hypervalente Iodreagens TIPS-EBX* ermöglicht zusammen mit [(Cp*RhCl₂)₂] als 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, ist 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 OH-dirigierten C-H-Alkinylierung mit hypervalenten Iodreagentien.

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 CH-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 CH 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 CH alkynylation with hypervalent iodine reagents.

An efficient protocol for the palladium-catalyzed synthesis of sterically congested triarylamines from commercially available 1-chloro- or 1-bromonaphthalenes and diarylamines is described. The application of alkyllithium reagents as strong bases and a combination of Pd(OAc)₂ and SPhos (2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl) plays a crucial role in the success of this otherwise difficult to achieve C–N coupling reaction. A variety of secondary aromatic amines with versatile steric and electronic properties can be successfully used in this transformation to give the desired triarylamines in up to 99 % yield. The obtained products are important structural motifs in hole-transport materials for organic light-emitting diode applications.

N-[(Uracil-5-yl)methyl]urea is reported as a minimalistic low-molecular-weight hydrogelator (LMWHG). The unusual phosphate-induced assembly of this compound has been thoroughly investigated by IR, UV/Vis, and NMR spectroscopy, electron microscopy, and rheological experiments. This rare example of an anion-triggered urea-based LMWHG is the first example of a pyrimidine- and urea-containing molecule that can be forced into self-assembly in aqueous solution without additional aromatic or lipophilic groups. The gelator/phosphate ratio within the hydrogel was successfully determined by ³¹P MAS NMR spectroscopy. The hydrogel exhibits a very fast and repeatable self-healing property, and remarkable G′ values. The viscoelastic properties of the hydrogel can easily be tuned by variation of the phosphate ratio.