title: Palladium-catalyzed regio- and stereoselective cross-addition of terminal alkynes to ynol ethers and synthesis of 1,4-enyn-3-ones.
abstract: Conjugated enynes, enol ethers, and enynones are versatile building blocks that can be elaborated by a wide variety of synthetic transformations. The selective synthesis of such units is a prerequisite for their effective utilization. The synthesis of conjugated 2-phenoxyenynes through a palladium-catalyzed cross-addition of terminal alkynes to phenylethynyl ethers (hydroalkynylation) is now presented. The reaction is highly regio-, stereo-, and chemoselective, and shows excellent tolerance toward functional groups. The addition further features very mild reaction conditions (room temperature) and an inexpensive catalytic system (without a ligand and with a cheaply available Pd catalyst). The thus synthesized enynyl ethers with allylic hydroxy tethers, which survived the reaction, were shown to be ready precursors for valuable 1-en-4-yn-3-ones.
authors: Medicinal & Process Chemistry Division, CSIR-Central Drug Research Institute, Lucknow, 226031 (India).
authors: Madala Hari
authors: MH
authors: Babu
authors: Vikas
authors: V
authors: Dwivedi
authors: Ruchir
authors: R
authors: Kant
authors: Maddi Sridhar
authors: MS
authors: Reddy
mesh_terms: D000114:Acetylene / Q000737:chemistry; D000480:Alkynes / Q000138:chemical synthesis / Q000737:chemistry*; D002384:Catalysis; D056831:Coordination Complexes / Q000737:chemistry; D018360:Crystallography, X-Ray; D004987:Ethers / Q000737:chemistry*; D008968:Molecular Conformation; D010165:Palladium / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D000480:Alkynes; D056831:Coordination Complexes; D004987:Ethers; D010165:Palladium; D000114:Acetylene
keywords: enol ethers; enynes; enynones; hydroalkynylation; stereoselectivity