copper-catalyzed domino homologation and cycloisomerization reactions for 3-pyrroline synthesis推荐.pdf

FULL PAPER DOI: 10.1002/ejoc.201301621 Copper-Catalyzed Domino Homologation and Cycloisomerization Reactions for 3-Pyrroline Synthesis Ye Ho Shin,[a][‡] Muchchintala Maheswara,[a][‡] Joon Young Hwang,[a] and Eun Joo Kang*[a] Keywords: Synthetic methods / Domino reactions / Cyclization / Nitrogen heterocycles / Copper / Allenes Copper bromide was found to be an efficient catalyst for a a wide range of 2-substituted- and 2,5-disubstituted-3- domino reaction sequence leading to 3-pyrrolines. The Cu(I)- pyrrolines. Mechanistic studies of the reaction intermediates catalyzed Crabbé reaction of propargyl sulfonamide and se- revealed two possible reaction pathways; both invoke the im- lective cycloisomerization of the allene intermediate were portance of vinyl copper intermediates. carried out using microwave irradiation conditions affording Introduction α-amino allenes; potassium carbonate was found to mediate 5-endo cycloisomerization under refluxing DMF condi- Nitrogen heterocycles, such as pyrroles, pyrrolines, and tions.[9] As part of our ongoing interest in economical dom- pyrrolidines, are important structural elements in a large ino reactions, we predicted that, as a general precursor of number of natural products and pharmaceutical molecules; allene,[10] terminal alkynes might be transformed to 3- many synthetic routes have been developed for their