Olefin Metathesis by Well-Characterized Re(VII) Alkylidene/Alkylidyne Complexes

摘要: A convenient one pot synthesis of Re(NR)2(py)Cl3 from Re2O7, trimethyl-chlorosilane, pyridine, and RNH2 (R = aryl or t-butyl) has been developed. Alkylation these species with dineopentyl dineophyl zinc Grignard reagents affords complexes the formula Re(NR)2(CHR’)(CH2R’) (R’ CMe3 CMe2Ph). Re(O)2(CH-t-Bu)(CH2-t-Bu) can be prepared by acid-catalyzed hydrolysis Re(NR)2(CH-t-Bu)(CH2-t-Bu), which upon treatment HC1 in dimethoxyethane produces [Re(C-t-Bu)(CH-t-Bu)Cl2]x. [Re(C-t-Bu)(CH-t-Bu)C12]xis a versatile precursor o variety bisalkoxide general syn anti-Re(C-t-Bu)(CH-t-Bu)(OR)2(OR O-t-Bu, OCMe2(CF3), OCMe(CF3)2, etc.). Metathetical reactions between Re(C-t-Bu)(CH-t-Bu)(ORF6)2 (ORF6 OCMe(CF3)2) 1-decene ethyl-9-decenoate yield expected new alkylidene complexes, are unstable concentrated solution cannot isolated. In presence THF type anti-Re(C-t-Bu)(CHR)(ORF6)2S2 Me, Et, Ph; S 0.5 DME) could high Re(C-t-Bu)(CH-t-BU)(ORF6)2 CH2=CHR. Heteroatom-substituted (O, S, N) terminal olefins other electron-rich react more rapidly than ordinary to anti-Re(C-t-BU)(CHX)(ORF6)2(THF)2 (X OR, SR, NR2). 2-Pentene methyl oleate aremetathesized intermediate observed each case. Ethylene reacts Re(C-t-Bu)(CHX)(OR)2 give metallacyclobutane first, then rhenacyclopentene via “3+2 cycloaddition” across C≡Re=C unit. X-ray studies syn-[Re(C-t-Bu)(CH-t-Bu)(Naryl)C12]2, syn-Re(C-t-Bu)(CH-t-Bu)(ORF6)2(THF), anti-Re(C-t-Bu)(CHferrocenyl)(ORF6)2, syn-Re(C-t-Bu)(CHOEt)(ORF6)2(THF)2 have carried out.