Neutral chiral cyclopentadienyl Ru(II)Cl catalysts enable enantioselective [2+2]-cycloadditions

Cyclopentadienyl ruthenium(II) complexes with a large number of available coordination sites are frequently used catalysts for a broad range of transformations. To be able to render these transformations enantioselective, we have designed a chiral neutral (CpRu)-Ru-x(II) Cl complex basing on an atropchiral cyclopentadienyl (Cp-x) ligand which is accessed in a streamlined C-H functionalisation approach. The catalyst displays excellent levels of reactivity and enantioselectivity for enantioselective [2+2]-cycloadditions leading to strained chiral cyclobutenes, allowing for catalyst loadings as low as 1 mol%. A very strong counterion effect of a bound chloride anion transforms the corresponding unselective cationic complex into a highly enantioselective neutral version. Moreover, by adding norbornadiene at the end of the reaction the catalyst can be recovered and subsequently reused.


Published in:
Chemical Science, 8, 3, 1862-1866
Year:
2017
Publisher:
Cambridge, Royal Soc Chemistry
ISSN:
2041-6520
Laboratories:




 Record created 2017-05-01, last modified 2018-03-17


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