Exploring Diazo Compounds for the Divergent Electro-Cascade Sequence and S-H Insertion Reaction.

Area of Science:

• Organic Electrochemistry
• Synthetic Organic Chemistry
• Heterocyclic Chemistry

Background:

• Diazo compounds are versatile synthetic intermediates.
• Electrochemical methods offer sustainable alternatives in organic synthesis.
• Accessing complex heterocyclic scaffolds like thiochromans remains a synthetic challenge.

Purpose of the Study:

• To develop a novel electrochemical cascade reaction for thiochroman synthesis.
• To explore the reactivity of diazo compounds under electrochemical conditions.
• To establish a mild, metal-free, and diastereoselective synthetic route.

Main Methods:

• Electrolysis of styryl diazo imides and aryl thiols.
• In situ generation and reaction of intermediates.
• Detection of key intermediates and computational studies to elucidate the mechanism.

Main Results:

• Successful establishment of a cascade thiolation/cyclization/reduction sequence.
• Direct access to a single diastereoisomer of 2,5-pyrrolidine-dione-fused thiochromans.
• Achieved good yields under mild and metal-free electrochemical conditions.
• Demonstrated tunable reactivity via S-H insertion at the diazo center.

Conclusions:

• Electrochemical oxidation of diazo compounds provides an efficient pathway to complex thiochromans.
• The developed cascade reaction is mild, metal-free, and highly diastereoselective.
• The mechanistic insights pave the way for further development of electrochemical synthetic strategies.