Selective Monoethynylation of 2-Oxoacetamides Using Calcium Carbide as a Concise Solid Alkyne Source

Area of Science:

• Organic Chemistry
• Synthetic Chemistry

Background:

• Acetylene gas, commonly used in ethynylation reactions, is highly flammable and explosive, posing significant safety risks in laboratory settings.
• Developing safer and more convenient alkyne sources is crucial for advancing synthetic methodologies.

Purpose of the Study:

• To develop an efficient and selective monoethynylation protocol for 2-oxoacetamides.
• To utilize calcium carbide as a safe and accessible solid alkyne source.
• To synthesize a series of multifunctional 2-hydroxybut-3-ynamides.

Main Methods:

• The study employed calcium carbide as a solid alkyne source for the monoethynylation of 2-oxoacetamides.
• The reaction was conducted under transition-metal-free and mild conditions.
• Standard work-up procedures were used for product isolation.

Main Results:

• The developed protocol successfully synthesized various 2-hydroxybut-3-ynamides with high selectivity and yield.
• Calcium carbide proved to be an effective and safe surrogate for gaseous acetylene.
• The reaction exhibited a wide substrate scope, demonstrating its versatility.

Conclusions:

• This study presents a novel, efficient, and safe method for synthesizing 2-hydroxybut-3-ynamides.
• The use of calcium carbide offers a practical alternative to hazardous acetylene gas in organic synthesis.
• The transition-metal-free protocol is advantageous for its mild conditions and broad applicability.