Abstract
Rhenium(V) oxo alkyl triflate compounds (HBpz3)ReO(R)OTf [R = Me (4), Et (5), n-Bu (6); HBpz3 = hydrotris(1-pyrazolyl)borate; OTf = OSO2CF3, triflate] are formed on sequential reaction of (HBpz3)ReOCl2 with dialkyl zinc reagents and AgOTf. These triflate compounds are rapidly oxidized at ambient temperatures by oxygen atom donors pyridine N-oxide (pyO) and dimethyl sulfoxide (DMSO) to give (HBpz3)ReO3 (7) and the corresponding aldehyde. In the cases of 5 and 6 this transformation is quantitative. The addition of 2,6-lutidine to a low-temperature oxidation of 5 by DMSO redirects the reaction to form cis-2-butene instead of acetaldehyde. These oxidation reactions do not proceed through alkoxide intermediates, as shown by independent studies of alkoxide oxidations. Reaction of 5 with pyO or DMSO at −47 °C results in the formation of intermediates which are assigned as ylide or “trapped-carbene” complexes [(HBpz3)ReO(OH){CH(L)CH3}]OTf (L = py (8) or SMe2 (9), respectively). Mechanistic studies and analogies with related systems suggest that oxygen atom transfer to 4-6 forms [(HBpz3)ReO2R]+. Transfer of an α-hydrogen from the alkyl group to an oxo ligand then forms an alkylidene complex which is trapped by SMe2 or py to give the observed intermediates. Further oxidation of the ylide complex gives the aldehyde.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
