Synthesis and metathesis reactions of a phosphine-free dihydroimidazole carbene ruthenium complex
作者:Simon Gessler、Stefan Randl、Siegfried Blechert
DOI:10.1016/s0040-4039(00)01808-6
日期:2000.12
Synthesis and activity in ring closure metathesis (RCM) and cross metathesis (CM) of the phosphine-free 1,3-dimesityl-4,5-dihydroimidazole-2-ylidene (IHMes) ruthenium alkoxybenzylidene complex 6 are reported.
The conjugateaddition of magnesium cuprates to 2-silyloxycyclopentenecarboxylates leads, after desilylation, to 5-substituted-2-hydroxycyclopentanecarboxylates in high yields and diastereoselectivities. The 2-silyloxy derivatives avoid the formation of the SN2′ reaction by-products. No loss of selectivity is also observed when a catalytic amount of cuprous salt is used.
Copper(I) mediated highly diastereoselective conjugate addition of Grignard reagents to functionalised cycloalkenols: a general and efficient route for the stereoselective synthesis of 5- and 6-membered ring trisubstituted cycloalkanols
The conjugateaddition of magnesium cuprates to various 2-silyloxycyclopentene and 2-silyloxycyclohexene carboxylates leads diastereoselectively to related syn–anti cyclopentanols and cyclohexanols in fair overall yields. The β-elimination occurring with free hydroxylic derivatives is also partially or totally avoided by concomitant in situ trapping of the generated enolates. Attempts to rationalise