Scope and Mechanism of the Redox-Active 1,2-Benzoquinone Enabled Ruthenium-Catalyzed Deaminative α-Alkylation of Ketones with Amines

Toward a Chemical Constructor: A Lego-Like Approach for Formal α-Alkylation of Cyclic Ketones

A conceptual strategy for a formal α-alkylation of α-methylene ketones was developed. Diverse 1° and 2° alkyl substituents were generated in the α-position of various ketones via synthesis of enaminone (step 1) and treatment with organomagnesium (step 2) with subsequent catalytic hydrogenation (step 3, 1° alkyl) or organocopper reagents (step 4, 2° alkyl). Tolerance toward ester, Boc-protected amine, and α-fluoro-substituted ketone moieties was demonstrated. The suitability of the method for late-stage natural product modification was shown.

Selective Synthesis of Ketones and Chiral Allylic Alcohols from the Addition of Arylboronic Acids to α,β-Unsaturated Aldehydes Mediated by a Transition Metal/Monophosphorus Ligand System

Here, we demonstrated a transition metal-mediated/monophosphorus ligand system for the selective synthesis of ketones or chiral allylic alcohols in high yields/enantiomeric excess from the 1,2-addition of arylboronic acids to α,β-unsaturated aldehydes. Notably, isomerization of the chiral allylic alcohols to ketones was suppressed by the Ru-catalyzed/monophosphorus ligand system. The asymmetric catalytic system provides an alternative and efficient method of preparing chiral allylic alcohols.

Selective Biocatalytic Defunctionalization of Raw Materials

Biobased raw materials, such as carbohydrates, amino acids, nucleotides, or lipids contain valuable functional groups with oxygen and nitrogen atoms. An abundance of many functional groups of the same type, such as primary or secondary hydroxy groups in carbohydrates, however, limits the synthetic usefulness if similar reactivities cannot be differentiated. Therefore, selective defunctionalization of highly functionalized biobased starting materials to differentially functionalized compounds can provide a sustainable access to chiral synthons, even in case of products with fewer functional groups. Selective defunctionalization reactions, without affecting other functional groups of the same type, are of fundamental interest for biocatalytic reactions. Controlled biocatalytic defunctionalizations of biobased raw materials are attractive for obtaining valuable platform chemicals and building blocks. The biocatalytic removal of functional groups, an important feature of natural metabolic pathways, can also be utilized in a systemic strategy for sustainable metabolite synthesis.

Synthesis of Flavanone and Quinazolinone Derivatives from the Ruthenium-Catalyzed Deaminative Coupling Reaction of 2'-Hydroxyaryl Ketones and 2-Aminobenzamides with Simple Amines

The cationic Ru-H complex [(C₆H₆)(PCy₃)(CO)RuH]⁺BF₄^- (1) with 3,4,5,6-tetrachloro-1,2-benzoquinone (L1) was found to be a highly effective catalyst for the deaminative coupling reaction of 2'-hydroxyaryl ketones with simple amines to form 3-substituted flavanone products. The analogous deaminative coupling reaction of 2-aminobenzamides with branched amines directly formed 3,3-disubstituted quinazolinone products. The catalytic method efficiently installs synthetically useful flavanone and quinazolinone core structures without employing any reactive reagents.