Cyclic Bent Allene Hydrido-Carbonyl Complexes of Ruthenium: Highly Active Catalysts for Hydrogenation of Olefins

A new family of ruthenium complexes
bearing the carbodicarbene-type
ligand “cyclic bent allene” (CBA) have been synthesized
from the common precursor RuHCl­(CO)­(PPh3)3.
Complexes were evaluated for catalytic activity in the room-temperature
hydrogenation of unactivated olefins and were found to be significantly
more active than known ruthenium hydrido-carbonyl phosphine or NHC
complexes. In particular, RuH­(OSO2CF3)­(CO)­(SIMes)­(CBA)
was found to be among the most active hydrogenation catalysts, achieving
comparable activity to Crabtree’s catalyst in the hydrogenation
of unactivated trisubstituted olefins and superior activity in the
hydrogenation of styrene derivatives in side-by-side catalytic runs.
RuH­(OSO2CF3)­(CO)­(SIMes)­(CBA) was also found
to be highly active in olefin selective hydrogenation in the presence
of a variety of unsaturated functional groups, and can achieve exceptional
diastereoselectivity in functional-group-directed hydrogenations at
very low catalyst loadings.

科研人员以常见前驱体RuHCl(CO)(PPh3)3为原料，合成了一类带有碳二卡宾类配体“环状弯曲联烯”（cyclic bent allene, CBA）的新型钌配合物。该系列配合物被用于未活化烯烃的室温加氢催化活性评价，结果显示其催化活性显著优于已报道的钌氢羰基膦或氮杂环卡宾（N-Heterocyclic Carbene, NHC）配合物。尤为值得关注的是，RuH(OSO2CF3)(CO)(SIMes)(CBA)被证实是当前活性最高的加氢催化剂之一：在未活化三取代烯烃的加氢反应中，其催化活性可与克拉布特里催化剂（Crabtree’s catalyst）相媲美；而在平行催化对比实验中，其对苯乙烯衍生物的加氢活性更胜一筹。RuH(OSO2CF3)(CO)(SIMes)(CBA)在多种不饱和官能团共存的体系中，仍可高效实现烯烃的选择性加氢；且在极低催化剂用量下，即可在官能团导向的加氢反应中实现优异的非对映选择性。