Direct Synthesis of α-Amino Acid Derivatives by Hydrative Amination of Alkynes

α-Amino acid derivatives are key components of the molecules of life. The synthesis of α-amino carbonyl/carboxyl compounds is a contemporary challenge in organic synthesis. Herein, we report a practical method for the preparation of α-amino acid derivatives via direct hydrative amination of activated alkynes under mild conditions, relying on sulfinamides as the nitrogen source. Computational studies suggest that the reaction is enabled by a new type of sulfonium [2,3]-sigmatropic rearrangement.

Synthese von α-Aminosäurederivaten durch hydrative Aminierung von Alkinen

α‐Aminosäurederivate sind Kernbestandteile jeglichen Lebens. Die Synthese von α‐Aminocarbonyl/carboxyl Verbindungen ist jedoch weiterhin eine Herausforderung für die organische Synthese. In dieser Arbeit berichten wir von einer praktischen Herstellungsmethode für α‐Aminosäurederivate durch direkte hydrative Aminierung von aktivierten Alkinen mit Sulfinamiden unter milden Bedingungen. Computergestützte Untersuchungen legen nahe, dass eine [2,3]‐sigmatrope Sulfoniumumlagerung der zentrale Schritt der Reaktion ist.

α-Functionalisation of Ketones Through Metal-Free Electrophilic Activation

Triflic anhydride mediated activation of acetophenones leads to highly electrophilic intermediates that can undergo a variety of transformations when treated with nucleophiles. This electrophilic ketone activation gives access to α‐arylated and α‐oxyaminated acetophenones under metal‐free conditions in moderate to excellent yields and enables extension to the synthesis of arylated morpholines via generation of vinylsulfonium salts. Computational investigations confirmed the transient existence of intermediates derived from vinyl triflates and the role of the oxygen atoms at the para position of aromatic ring in facilitating their stabilisation.

α-Arylation of Carbonyl Compounds through Oxidative C-C Bond Activation

A synthetically useful approach for the direct α-arylation of carbonyl compounds through a novel oxidative C-C bond activation is reported. This mechanistically unusual process relies on a 1,2-aryl shift and results in all-carbon quaternary centers. The transformation displays broad functional-group tolerance and can in principle also be applied as an asymmetric variant.