1646499-68-4Relevant academic research and scientific papers
Pd-catalyzed cycloisomerization of 4-aza-1,6-enynes to 3-aza-bicyclo[4.1.0] hept-2-enes
Oh, Hye Mi,Park, Ji Eun,Kim, Jisu,Kim, Ju Hyun,Kang, Youn K.,Chung, Young Keun
, p. 9024 - 9036 (2014)
A method for the synthesis of bicyclo[4.1.0]heptenes from 1,6-enynes through Pd-catalyzed cycloisomerization has been developed. N- and O-tethered 1,6-enynes were successfully transformed to their corresponding 3-aza- and 3-oxabicyclo[4.1.0]heptenes in reasonable-to-high yields using the catalysts [PdCl2(CH3CN)2]/P(OPh)3 or [Pd(maleimidate)2(PPh3)2] in toluene. The computational calculations using density functional theory indicate that [PdCl2{P(OPh)3}] in the oxidation state PdII acts as the active catalyst species for the formation of 3-azabicyclo[4.1.0] heptenes through 6-endo-dig cyclization. Pd-catalyzed cycloisomerization of 1,6-enynes has long been studied and provides a variety of 5-membered ring systems. A method that transforms 1,6-enynes to bicyclo[4.1.0]heptene-type products through palladium catalysis was elusive but eventually has been found. A broad range of 4-aza-1,6-enynes were successfully transformed to 3-aza-bicyclo[4.1.0]heptenes in moderate-to-high yields when [PdCl 2]/P(OPh)3 or [Pd(maleimidate)2(PPh 3)2] catalysts were used in a nonpolar solvent (see figure).
