Stereo- and regio-controlled carbon–carbon bond formation mediated by tungsten in the s-trans-η4-diene cationic intermediates
Abstract
The tungsten-η3-2-substituted pentadienyl complexes WC5H5(CO)2(syn-η3-R-C5H6)(R = COOMe; CMeCH2) undergo BF3-catalysed stereoselective carbon-carbon bond formation with aldehydes to afford isolable s-trans-diene cations which after hydrolysis produces tungsten-η3-allyl-1,3-diols; utilization of the diols for stereoselective synthesis of α-methylene-γ-butyrolactones, furanone skeletons, have been reported in good yields (> 80%).