TY - JOUR
T1 - A coordinatively unsaturated ruthenium methoxide as a highly effective catalyst for the halogen atom-transfer radical cyclization of N-allyl dichloroacetamides and related reactions
AU - Motoyama, Yukihiro
AU - Hanada, Shiori
AU - Shimamoto, Kazuya
AU - Nagashima, Hideo
N1 - Funding Information:
We are grateful to Mr. Taisuke Matsumoto and Ms. Keiko Ideta (Analytical Center in Institute for Materials Chemistry and Engineering, Kyushu University) for their help in the X-ray and NOE analyses. This work was supported by a Grant-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology, Japan.
PY - 2006/3/20
Y1 - 2006/3/20
N2 - Atom-transfer radical cyclization (ATRC) catalyzed by coordinatively unsaturated ruthenium alkoxides 4, [(η5-C5Me 5)Ru(OR)]2, is investigated, and ruthenium methoxide 4a (R=Me) is found to exhibit excellent catalytic activity for the cyclization of N-allyl-α,α-dichloroacetamides at ambient temperature. Addition of some amounts of two-electron donor ligands such as pyridine and triphenylphosphine improves the catalyst efficiency to afford the corresponding γ-lactams in high yields. The high catalytic activity of this catalyst system enables to control the diastereoselectivity of this 5-exo cyclization kinetically. The present 4a/pyridine system is also effective for the 4-exo cyclization of N-vinylacetamides to afford the corresponding β-lactams in quantitative yields. The 4a/pyridine system is also active towards the ATRP of methyl methacrylate (MMA) at room temperature to afford the poly(MMA) with narrow molecular weight distributions (Mw/Mn=1.2) at the initial stage.
AB - Atom-transfer radical cyclization (ATRC) catalyzed by coordinatively unsaturated ruthenium alkoxides 4, [(η5-C5Me 5)Ru(OR)]2, is investigated, and ruthenium methoxide 4a (R=Me) is found to exhibit excellent catalytic activity for the cyclization of N-allyl-α,α-dichloroacetamides at ambient temperature. Addition of some amounts of two-electron donor ligands such as pyridine and triphenylphosphine improves the catalyst efficiency to afford the corresponding γ-lactams in high yields. The high catalytic activity of this catalyst system enables to control the diastereoselectivity of this 5-exo cyclization kinetically. The present 4a/pyridine system is also effective for the 4-exo cyclization of N-vinylacetamides to afford the corresponding β-lactams in quantitative yields. The 4a/pyridine system is also active towards the ATRP of methyl methacrylate (MMA) at room temperature to afford the poly(MMA) with narrow molecular weight distributions (Mw/Mn=1.2) at the initial stage.
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U2 - 10.1016/j.tet.2006.01.011
DO - 10.1016/j.tet.2006.01.011
M3 - Article
AN - SCOPUS:32844474452
VL - 62
SP - 2779
EP - 2788
JO - Tetrahedron
JF - Tetrahedron
SN - 0040-4020
IS - 12
ER -