Palladium catalyzed synthesis of alkene and alkyne derivatives from terminal alkynes

Abstract

Arylalkynes are very useful intermediates for the preparation of important compounds including natural products, pharmaceuticals, oligomers, polymers. Their derivatives are versatile compounds in synthetic organic chemistry, and hence, various methods for their synthesis have been explored. Palladium-catalyzed carbon-carbon bond formations are very useful methods for constructing higher molecules such as materials and drugs for modern chemical and medical applications. Here, it is desired to develop the methods of synthesis of alkene and alkyne derivatives through palladium catalyzed reactions. For this purpose, iodo compounds [1,2- diiodo-1-phenylethene; 1,2-diiodo-1-heptene and 1,4-diphenyl-1,2,3,4-tetraiodobuta-1,3-diene] were synthesized by the iodination of their parent corresponding alkynes using molecular iodine (I2). The palladium-catalyzed cross-coupling reaction of the starting materials (1,2-diiodo-1- phenylethene and 1,2-diiodo-1-heptene) with terminal alkynes (phenylacetylene, 1-hexyne, 1- heptyne) or alkyl acrylate (methyl acrylate, ethyl acrylate) were carried out in the presence of bis (triphenyl phosphine) palladium (II) chloride, copper (I) iodide, and triethylamine in DMF or CH2Cl2 at 80°C for 24 h under nitrogen atmosphere to yield alkenyne and alkenoate derivatives. Copper (I) iodide was not used for the synthesis of alkenoate derivatives, ......................