1416159-35-7

Upstream product

• 197846-61-0 1-(4-methoxyphenyl)-4-(trimethylsilyl)but-3-in-2-one 
• 4693-91-8 4-methoxyphenyl-acetic chloride 
• 14630-40-1 Bis(trimethylsilyl)ethyne 
• 1416159-26-6 (1E)-1-ethoxy-2-(4-methoxyphenyl)-5-(trimethylsilyl)pent-1-en-4-yn-3-one 
• 19501-58-7 4-methoxyphenylhydrazine hydrochloride 

Relevant academic research and scientific papers

Synthesis of [2-(Trimethylsilyl)ethynyl]pyrazoles based on bis(trimethylsilyl)acetylene and arylacetyl chlorides

A practical approach to the synthesis of [2-(trimethylsilyl)ethynyl] pyrazoles was developed through condensation of hydrazines with enynones that are easily accessible frombis(trimethylsilyl)acetylene and arylacetyl chlorides. Optimized conditions for reactions with monoarylhydrazines permit the chemoselective formation of 5-alkynylpyrazoles in high yields (48-94 %). When monoalkylhydrazines or the parent hydrazine is used, mixtures of 3- and 5-alkynylpyrazoles are formed in 73-79 % yields. The method uses inexpensive starting materials and can be applied to a variety of substrates, which makes it convenient for the synthesis of alkynylpyrazoles. A three-step method for the synthesis of 5-alkynylpyrazoles through a transformation of bis(trimethylsilyl) acetylene to enynones followed by their condensation with hydrazines is described. The chemoselectivity of the last stage is discussed.