Pyridylacetic acids and related systems as alkylheteroarene surrogates in asymmetric decarboxylative Michael addition

Reaction blueprints and logical control flow for parallelized chiral synthesis in the Chemputer

Despite recent proliferation of programmable robotic chemistry hardware, current chemical programming ontologies lack essential structured programming constructs like variables, functions, and loops. Herein we present an integration of these concepts into χDL, a universal high-level chemical programming language executable in the Chemputer. To achieve this, we introduce reaction blueprints as a chemical analog to functions in computer science, allowing to apply sets of synthesis operations to different reagents and conditions. We further expand χDL with logical operation queues and iteration via pattern matching. The combination of these new features allows encoding of chemical syntheses in generalized, reproducible, and parallelized digital workflows rather than opaque and entangled single-step operations. This is showcased by synthesizing chiral diarylprolinol catalysts and subsequently utilizing them in various synthetic transformations (13 separate automated runs affording 3 organocatalysts and 12 distinct enantioenriched products in 42-97% yield, up to > 99:1 er), including automated catalyst recycling and reuse.

B/Pd Synergistic Catalysis for the Decarboxylative Allylation of 2-(2-Azaaryl)acetic Acids

We describe an allylation reaction between 2-(2-azaaryl)acetic acids and allylic electrophiles catalyzed synergistically by a dual system consisting of borinic acid and a Pd complex under mild conditions. The decarboxylative allylation proceeds via a boron-bound enamine intermediate, which then interacts with a π-allylpalladium intermediate from the allylic electrophile. High yields of diallylation products highlight the method's efficiency. Intriguingly, when using 2-(2-pyridyl)acetic acid with a C3 substituent on the pyridyl ring, the reaction exclusively yields monoallylation products.

Doubly Decarboxylative Synthesis of 4-(Pyridylmethyl)chroman-2-ones and 2-(Pyridylmethyl)chroman-4-ones under Mild Reaction Conditions

The doubly decarboxylative Michael-type addition of pyridylacetic acid to chromone-3-carboxylic acids or coumarin-3-carboxylic acids has been developed. This protocol has been realized under Brønsted base catalysis, providing biologically interesting 4-(pyridylmethyl)chroman-2-ones and 2-(pyridylmethyl)chroman-4-ones in good or very good yields. The decarboxylative reaction pathway has been confirmed by mechanistic studies. Moreover, attempts to develop an enantioselective variant of the cascade are also described.