Synthesis and Applications of RuCl2(=CHR')(PR3)2: The Influence of the Alkylidene Moiety on Metathesis Activity
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- 作者：Peter Schwab ; Robert H. Grubbs ; and Joseph W. Ziller
- 刊名：Journal of the American Chemical Society
- 出版年：1996
- 出版时间：January 10, 1996
- 年：1996
- 卷：118
- 期：1
- 页码：100 - 110
- 全文大小：564K
- 年卷期：v.118,no.1(January 10, 1996)
- ISSN：1520-5126
文摘
The reactions ofRuCl2(PPh3)3 with a number ofdiazoalkanes were surveyed, and alkylidene transfer togive RuCl2(=CHR)(PPh3)2(R = Me (1), Et (2)) andRuCl2(=CH-p-C6H4X)(PPh3)2(X = H (3), NMe2 (4),OMe(5), Me (6), F (7), Cl (8),NO2 (9)) was observed for alkyl diazoalkanesRCHN2 and various para-substitutedaryldiazoalkanesp-C6H4XCHN2.Kinetic studies on the living ring-opening metathesispolymerization (ROMP) ofnorbornene using complexes 3-9 as catalystshave shown that initiation is in all cases faster than propagation(ki/kp= 9 for 3) and that the electronic effect of X on themetathesis activity of 3-9 is relatively small.Phosphineexchange in 3-9 with tricyclohexylphosphineleads toRuCl2(=CH-p-C6H4X)(PCy3)210-16, which are efficientcatalysts for ROMP of cyclooctene (PDI = 1.51-1.63) and1,5-cyclooctadiene (PDI = 1.56-1.67). The crystalstructure ofRuCl2(=CH-p-C6H4Cl)(PCy3)2(15) indicated a distorted square-pyramidal geometry, inwhich the twophosphines are trans to each other, and the alkylidene unitlies in the Cl-Ru-Cl plane. The benzylidenesRuCl2(=CHPh)(PR3)2 (R = Cy (cyclohexyl)(10), Cp (cyclopentyl) (17), i-Pr(18)) are quantitatively available viaone-potsynthesis with RuCl2(PPh3)3,PhCHN2, and PR3 as reaction components.10 is an efficient catalyst for metathesisofacyclic olefins: On reaction with excess ethylene, the methylidenecomplexRuCl2(=CH2)(PCy3)2(19) is formedquantitatively, and various alkylidene compoundsRuCl2(=CHR)(PCy3)3 (R= Me (20), Et (21), n-Bu(22)) areisolated as the kinetic products from the reaction of 10with an excess of the corresponding terminal ordisubstitutedolefins. Metathesis of conjugated and cumulated olefins with10 results in the formation of vinylalkylideneandvinylidene complexes, as shown by the synthesis ofRuCl2(=CHCH=CH2)(PCy3)2(23) andRuCl2(=C=CH2)(PCy3)2(24) from 1,3-butadiene or 1,2-propadiene, respectively.Also, functional groups such as -OAc, -Cl, and-OHcan be introduced into the alkylidene moiety via crossmetathesis with the appropriate alkene.