The Grubbs 1st generation catalyst has become a widely recognized compound in synthesis and materials research. It is also perhaps the most widely used precursor to generate other catalyst variants (e.g. 2nd Generation Grubbs). The remarkable tolerance to air and water, and stability towards functional groups has allowed for widespread applications.
The first report (ACIE 1995) highlights a convenient synthesis of (PCy3)2Cl2Ru=CHPh using a common ruthenium precursor and diazo reagents. In the past, metal carbene generators relied on α-hydrogen abstraction, phosphorane transfer, or ring-opening of cyclopropenes. These results illustrate diazoalkanes as excellent precursors for generating ruthenium metathesis catalysts. In addition, the first isolable metathesis-active methylidene complex, (PCy3)2Cl2Ru=CH2, is conveniently made from a reaction with ethylene. At the time, methylidenes of titanium, molybdenum, and tungsten were either not isolable or metathesis inactive.
The second paper (JACS 1996) reports the activity and applications of the 1st generation catalyst. The catalyst syntheses include the use of various diazoalkanes and phosphine exchange reactions. Early kinetic studies of the polymerization of norbornene gave nearly monodispersed polymers (PDI≤1.1) at a rate of ≈150 equiv/h. Structural analysis reveals a distorted trigonal bi-pyramid structure and a Ru-alkylidene bond length consistent with a Ru=C bond. The cross metathesis activity of the catalyst is demonstrated as a useful route to give new catalysts with different alkylidene moieties. In addition, conjugated alkylidenes are generated via metathesis where the cyclopropene and diazo reagents were not conveniently available. Finally, the functional group tolerance is demonstrated by cross metathesis of allyl acetate, allyl chloride, and 4-penten-1-ol.
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