3.2.3. Hydroformylation 2467 3.2.4. Dimerization 2468 3.2.5. Oxidative Cleavage and Ozonolysis 2469 3.2.6. Metathesis 2470 4. Terpenes 2472 4.1. Pinene 2472 4.1.1. Isomerization: R-Pinene 2472 4.1.2. Epoxidation of R-Pinene 2475 4.1.3. Isomerization of R-Pinene Oxide 2477 4.1.4. Hydration of R-Pinene: R-Terpineol 2478 4.1.5. Dehydroisomerization 2479 4.2. Limonene 2480 4.2.1. Isomerization 2480 4.2.2. Epoxidation: Limonene Oxide 2480 4.2.3. Isomerization of Limonene Oxide 2481 4.2.4. Dehydroisomerization of Limonene and Terpenes To Produce Cymene 2481

Chemical Routes for the Transformation of Biomass into Chemicals

In recent years, the olefin metathesis reaction has attracted widespread attention as a versatile carbon−carbon bond-forming method. Many new applications have become possible because of major advances in catalyst design. State-of-the-art ruthenium catalysts are not only highly active but also compatible with most functional groups and easy to use. This Account traces the ideas and discoveries that were instrumental in the development of these catalysts, with particular emphasis on (PCy3)2Cl2RuCHPh and its derivatives. The discussion includes an analysis of trends in catalyst activity, a description of catalysts coordinated with N-heterocyclic carbene ligands, and an overview of ongoing work to improve the activity, stability, and selectivity of this family of L2X2RuCHR complexes.

http://web4.uwindsor.ca/users/j/jlichaa/reference.nsf/0/10ff8b04ff3a317885256d88005720f6/$FILE/acr-2001-34-18-metath-grubbs.pdf

The Development of L2X2RuCHR Olefin Metathesis Catalysts: An Organometallic Success Story

The reactions of RuCl2(PPh3)3 with a number of diazoalkanes were surveyed, and alkylidene transfer to give RuCl2(CHR)(PPh3)2 (R = Me (1), Et (2)) and RuCl2(CH-p-C6H4X)(PPh3)2 (X = H (3), NMe2 (4), OMe (5), Me (6), F (7), Cl (8), NO2 (9)) was observed for alkyl diazoalkanes RCHN2 and various para-substituted aryl diazoalkanes p-C6H4XCHN2. Kinetic studies on the living ring-opening metathesis polymerization (ROMP) of norbornene using complexes 3−9 as catalysts have shown that initiation is in all cases faster than propagation (ki/kp = 9 for 3) and that the electronic effect of X on the metathesis activity of 3−9 is relatively small. Phosphine exchange in 3−9 with tricyclohexylphosphine leads to RuCl2(CH-p-C6H4X)(PCy3)2 10−16, which are efficient catalysts for ROMP of cyclooctene (PDI = 1.51−1.63) and 1,5-cyclooctadiene (PDI = 1.56−1.67). The crystal structure of RuCl2(CH-p-C6H4Cl)(PCy3)2 (15) indicated a distorted square-pyramidal geometry, in which the two phosphines are trans to each other, and the alkyli...

Synthesis and Applications of RuCl2(CHR‘)(PR3)2: The Influence of the Alkylidene Moiety on Metathesis Activity

Recent advances in olefin metathesis and its application in organic synthesis

The fascinating story of olefin (or alkene) metathesis (eq
1) began almost five decades ago, when Anderson and
Merckling reported the first carbon-carbon double-bond
rearrangement reaction in the titanium-catalyzed polymerization of norbornene. Nine years later, Banks and Bailey reported “a new disproportionation reaction . . . in which olefins are converted to homologues of shorter and longer carbon chains...”. In 1967, Calderon and co-workers named this metal-catalyzed redistribution of carbon-carbon double bonds olefin metathesis, from the Greek word “μeτάθeση”, which means change of position. These contributions have since served as the foundation for an amazing research field, and olefin metathesis currently represents a powerful transformation in chemical synthesis, attracting a vast amount of interest both in industry and academia.

https://core.ac.uk/download/pdf/4884240.pdf

Ruthenium-based heterocyclic carbene-coordinated olefin metathesis catalysts.

Preparation et activite d'un complexe de W de type W(CH−t−Bu)(NR)(OR') 2 , OR'=OC(Me)(CF 3 ) 2

Multiple metal-carbon bonds. 43. Well-characterized, highly active, Lewis acid free olefin metathesis catalysts

Preparation des complexes MO(CCMe 3 )(CH 2 CMe 3 ) 3 , et des complexes Mo(CCMe 3 )X 3 (dme). Les acetylenes internes ne reagissent pas avec MO(CCMe 3 )(OCMe 3 ) 3 ; ils sont grandement polymerises par MO(CCMe 3 )(OCHMe 2 ) 3 et MO(CCMe 3 )(OCH 2 CMe 3 ) 3 . Structure cristalline

Preparation of trialkoxymolybdenum(VI) alkylidyne complexes, their reactions with acetylenes, and the X-ray structure of Mo[C3(CMe3)2][OCH(CF3)2]2(C5H5N)21

Addition of LiDIPP = O-2,6-C{sub 6}H{sub 3}-i-Pr{sub 2} to Ta(CH-t-Bu)(THF){sub 2}Cl{sub 3} yields Ta(CH-t-Bu)(DIPP){sub 3}(THF) (1) in high yield. Ta(CH-t-Bu)(DMP){sub 3}(THF) (3; DMP = O-2,6-C{sub 6}H{sub 3}Me{sub 2}) and Ta(CH-t-Bu)(TIPT){sub 3}(THF) (5; TIPT = S-,2,4,6-C{sub 6}H{sub 2}i-Pr{sub 3}) can be prepared by analogous methods. 1 reacts rapidly with 1 equiv of styrene to give the tantalacyclobutane complex Ta(CH(Ph)CH(t-Bu)CH{sub 2})(DIPP){sub 3}. The crystal and molecular structure of the complex are reported. An analogous reaction between 1 and vinyltrimethylsilane gives Ta(CHSiMe{sub 3})(DIPP){sub 3}(THF) or Ta(CH(SiMe{sub 3})CH(SiMe{sub 3})CH{sub 2})(DIPP){sub 3} depending upon reaction conditions; the two are in ready equilibrium. 1 reacts smoothly with ethylene to give Ta(CH{sub 2}CH{sub 2}CH{sub 2})(DIPP){sub 3} in high yield, but treatment of 1 with olefins such as propylene or 1-butene did not lead to any characterizable species. Addition of excess cis-2-pentene to 1 results in rapid metathesis (100 equiv to equilibrium in < 15 min), but activity is short-lived. In contrast to reactions between 1 and olefins, Ta(CH-t-Bu)(TIPT){sub 3}(THF) does not react with ordinary olefins and will not metathesize them. Tantalacyclobutane complexes containing the DIPP ligand react with the carbonyl functionality to give a mixture of insertion chemistry (oxytantalacyclohexane complexes) and Wittig-like reactivity, depending upon the carbonylmore » compound, the tantalacycle, and the temperature. 1 reacts with norbornene to give an isolable tantalacyclobutane complex, Ta(CH(C{sub 5}H{sub 8})CHCH(t-Bu))(DIPP){sub 3}, whose crystal structure is reported. 25 references, 9 figures, 7 tables.« less

Preparation and reactions of tantalum alkylidene complexes containing bulky phenoxide or thiolate ligands. Controlling ring-opening metathesis polymerization activity and mechanism through choice of anionic ligand

A simple route to hexacarbonyldiiron complexes containing a bridging thiolate and an organic bridging ligand by means of [(.mu.-RS)(.mu.-CO)Fe2(CO)6]- intermediates

General methods for the preparation of ligands of the type R'SCH/sub 2/CONHCH/sub 2/CH/sub 2/NHCOCH/sub 2/SR, H/sub 2/ema(R)(R'), where R = alkyl, aminoalkyl, and carboxyalkyl and R' = H, benzoyl, acetamidomethyl, and benzamidomethyl are described. New methods for the protection and deprotection of thiols with triphenylmethyl and amidomethyl groups have been developed. These ligands have been reacted with (Bu/sub 4/N)(TcOCl/sub 4/) and Na(TcO(eg)/sub 2/) (eg = ethylene glycolato), and for the cases where R = Me, CH/sub 2/Ph,(CH/sub 2/)/sub 10/COOH, and CH/sub 2/CH/sub 2/(NC/sub 4/H/sub 8/O), neutral complexes, (TcO(emaR)), have been isolated and characterized. The complex (TcO(ema(CH/sub 2/CH/sub 2/NC/sub 4/H/sub 8/O))) was crystallized as a monohydrate, and a single-crystal X-ray structure determination was performed. For all of the (TcO(ema(CH/sub 2/CH/sub 2/NR/sub 2/))) complexes, an intramolecular dealkylation occurred to cleanly form (TcO(ema))/sup /minus//, which can be isolated as the AsPh/sub 4//sup +/ salt. Furthermore, (TcO(ema(CH/sub 2/Ph))) and (TcO(ema(Me))) were reacted with amines, water, and halides to give the dealkylated products. Crystal data for C/sub 12/H/sub 20/N/sub 3/O/sub 4/S/sub 2/Tc/center dot/H/sub 2/O: monoclinic, a = 12.120 (1) /angstrom/, b = 7.172 (1) /angstrom/, c = 18.933 (2) /angstrom/, /beta/ = 94.29 (1)/degree/, V = 1641.1 /angstrom//sup 3/, space group = P2/sub 1//n (No.more » 14), Z = 4, R = 0.042, R/sub w/ = 0.055. 34 references, 3 figures, 3 tables.« less

John C. Dewan

Papers

Multiple metal-carbon bonds. 43. Well-characterized, highly active, Lewis acid free olefin metathesis catalysts

Preparation of trialkoxymolybdenum(VI) alkylidyne complexes, their reactions with acetylenes, and the X-ray structure of Mo[C3(CMe3)2][OCH(CF3)2]2(C5H5N)21

Preparation and reactions of tantalum alkylidene complexes containing bulky phenoxide or thiolate ligands. Controlling ring-opening metathesis polymerization activity and mechanism through choice of anionic ligand

A simple route to hexacarbonyldiiron complexes containing a bridging thiolate and an organic bridging ligand by means of [(.mu.-RS)(.mu.-CO)Fe2(CO)6]- intermediates

Neutral technetium(V) complexes with amide-thiol-thioether chelating ligands